Java NullPointerException javax.xml.transform
我编写了一个简单的XMLPhoneBook程序，从用户（从输入控制台）获取输入，如firstname、lastname和电话号码，并将其保存到名为“PhoneBook.XML”的XML文件中。该程序还检查现有的xml文件，如果该文件已经存在，则更新该文件，或者创建一个新文件。我编写的没有错误处理类的代码的第一个版本是成功的 当我试图用错误处理类更新代码时，我开始从javax.xml.transform获取NullPointerException。我已经在下面发布了我的代码的两个版本供您理解 没有错误处理的主类XMLPhoneBook。Java NullPointerException javax.xml.transform,java,xml,nullpointerexception,Java,Xml,Nullpointerexception,我编写了一个简单的XMLPhoneBook程序，从用户（从输入控制台）获取输入，如firstname、lastname和电话号码，并将其保存到名为“PhoneBook.XML”的XML文件中。该程序还检查现有的xml文件，如果该文件已经存在，则更新该文件，或者创建一个新文件。我编写的没有错误处理类的代码的第一个版本是成功的 当我试图用错误处理类更新代码时，我开始从javax.xml.transform获取NullPointerException。我已经在下面发布了我的代码的两个版本供您理解 没有
/**
*
* @author Sanjayan Ravi
*/
/**
*
* Class XMLPhoneBook is the Main Class that controls getContactInfo function and storeContactInfo.
*/
public class XMLPhoneBook
{
GetContactInformation gci;
StoreContactInformation sci;
XMLPhoneBook()
{
gci = new GetContactInformation();
}
/**
*
* getContactInfo function triggers the functions getFirstName, getLastName, getPhoneNumber of the GetContactInformation class.
*/
void getContactInfo(){
gci.getFirstName();
gci.getLastName();
gci.getPhoneNumber();
}
/**
*
* The variables FName, LName, PhoneNumber of the class GetContactInformation contains the user entered data, these values are passed to the class StoreContactInformation for creating/updating an XML file with user data.
*/
void storeContactInfo(){
sci = new StoreContactInformation(gci.FName,gci.LName,gci.PhoneNumber);
}
public static void main(String[] args)
{
XMLPhoneBook pb = new XMLPhoneBook();
pb.getContactInfo();
pb.storeContactInfo();
}
}
/**
*
* Class GetContactInformation is responsible for getting inputs from the user such as First Name, Last Name and Phone Number.
* The variables FName(String), LName(String), PhoneNumber(long) are used for containing the user data during run time.
* The Variable reader(Scanner) is used for getting inputs from the user via the console.
*/
import java.util.Scanner;
public class GetContactInformation {
String FName;
String LName;
long PhoneNumber;
Scanner reader;
GetContactInformation(){
FName=null;
LName=null;
PhoneNumber=0;
}
/**
*
* The function getFirstName prompts the user for this first name and gets the inputs from the console.
* Then the value for the first name is passed to the function setFirstName.
*/
void getFirstName(){
System.out.println("Enter Your FirstName = ");
reader = new Scanner(System.in);
setFirstName(reader.nextLine());
}
/**
*
* The function getLastName prompts the user for this last name and gets the inputs from the console.
* Then the value for the last name is passed to the function setLastName.
*/
void getLastName(){
System.out.println("Enter Your LastName = ");
reader = new Scanner(System.in);
setLastName(reader.nextLine());
}
/**
*
* The function getPhoneNumber prompts the user for this phone number and gets the inputs from the console.
* Then the value for the phone number is passed to the function setPhoneNumber.
*/
void getPhoneNumber(){
try{
System.out.println("Enter Your PhoneNumber = ");
reader = new Scanner(System.in);
setPhoneNumber(Long.parseUnsignedLong(reader.nextLine()));
}catch(java.lang.NumberFormatException e){
}
}
/**
*
* The function setFirstName assigns the value it receives to the variable FName.
*/
String setFirstName(String FN){
return FName=FN;
}
/**
*
* The function setLastName assigns the value it receives to the variable LName.
*/
String setLastName(String LN){
return LName=LN;
}
/**
*
* The function setPhoneNumber assigns the value it receives to the variable PhoneNumber.
*/
long setPhoneNumber(long PN){
return PhoneNumber=PN;
}
}
/**
*
* The StoreContactInformation is responsible for storing the user data such as first name, last name and phone number into an XML file called PhoneBook.xml.
* The StoreContactInformation first checks if the XML file already exist then if the file exist it simply updates the file or else creates a new XML file with the provided user data.
*
*/
import java.io.File;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.OutputKeys;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.xml.sax.SAXException;
import java.io.IOException;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
public class StoreContactInformation {
File f;
String filePathString ;
DocumentBuilderFactory docFactory ;
DocumentBuilder docBuilder ;
Document doc;
TransformerFactory transformerFactory;
Transformer transformer;
DOMSource source;
StreamResult result;
String FirstName;
String LastName;
long PhoneNumber;
StoreContactInformation(String fn, String ln, long pn){
filePathString="PhoneBook.xml"; //File Path is the current working directory.
f = new File(filePathString);
FirstName=fn;
LastName=ln;
PhoneNumber=pn;
docFactory = DocumentBuilderFactory.newInstance();
try {
docBuilder = docFactory.newDocumentBuilder();
}
catch (ParserConfigurationException pce)
{
pce.printStackTrace();
}
transformerFactory = TransformerFactory.newInstance();
try
{
transformer = transformerFactory.newTransformer();
}
catch (TransformerException tfe)
{
tfe.printStackTrace();
}
// check if the XML file exist already !
if(f.exists() && !f.isDirectory()) {
//if exist
UpdateXMLFile();
WriteToXMLFile();
}else{
//if do not exist
CreateXMLFile();
WriteToXMLFile();
}
}
/**
*
* The function CreateXMLFile creates a new XML file if one doesn't exist already.
* The first set of data stored in the XML file is given the unique id="1".
* The root element of the XML file is "ContactInformation" which contains child nodes "Contact" with there unique ids.
* The element "contact further contains child nodes "FirstName","LastName" and "PhoneNumber".
*/
void CreateXMLFile(){
doc = docBuilder.newDocument();
Element rootElement = doc.createElement("ContactInformation");
doc.appendChild(rootElement);
Element contact = doc.createElement("Contact");
rootElement.appendChild(contact);
Attr attr = doc.createAttribute("id");
attr.setValue("1");
contact.setAttributeNode(attr);
Element firstname = doc.createElement("FirstName");
firstname.appendChild(doc.createTextNode(FirstName));
contact.appendChild(firstname);
Element lastname = doc.createElement("LastName");
lastname.appendChild(doc.createTextNode(LastName));
contact.appendChild(lastname);
Element PN = doc.createElement("PhoneNumber");
PN.appendChild(doc.createTextNode(java.lang.Long.toString(PhoneNumber)));
contact.appendChild(PN);
}
/**
*
* The function WriteToXMLFile is responsible for writing the data into output XML file "PhoneBook.xml".
* WriteToXMLFile also formats the data to be written into pretty print way with INDENT spaces and line breaks etc.
*/
void WriteToXMLFile(){
try
{
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
source = new DOMSource(doc);
result = new StreamResult(new File(filePathString));
transformer.transform(source, result);
System.out.println("Contact Saved !");
}
catch (TransformerException tfe)
{
tfe.printStackTrace();
}
}
/**
*
* The function UpdateXMLFile updates the existing XML file with the new user data.
* The new set of user data gets a unique id for the element "Contact" which is calculated and generated by UpdateXMLFile.
*
*/
void UpdateXMLFile(){
try
{
doc = docBuilder.parse(filePathString);
}catch(SAXException sae){
}catch (IOException ioe) {
ioe.printStackTrace();
}
int AttrValue=1;
Node ContactInfo = doc.getFirstChild();
NodeList NumberChildNodes = ContactInfo.getChildNodes();
for(int i=0;i<NumberChildNodes.getLength();i++)
{
Node n = NumberChildNodes.item(i);
if ("Contact".equals(n.getNodeName()))
{
AttrValue+=1;
}
}
Element contact = doc.createElement("Contact");
ContactInfo.appendChild(contact);
Attr attr = doc.createAttribute("id");
attr.setValue(Integer.toString(AttrValue));
contact.setAttributeNode(attr);
Element firstname = doc.createElement("FirstName");
firstname.appendChild(doc.createTextNode(FirstName));
contact.appendChild(firstname);
Element lastname = doc.createElement("LastName");
lastname.appendChild(doc.createTextNode(LastName));
contact.appendChild(lastname);
Element PN = doc.createElement("PhoneNumber");
PN.appendChild(doc.createTextNode(java.lang.Long.toString(PhoneNumber)));
contact.appendChild(PN);
}
}
/**
*
* @author Sanjayan Ravi
*/
/**
*
* Class XMLPhoneBook is the Main Class that controls getContactInfo function and storeContactInfo.
*/
public class XMLPhoneBook
{
GetContactInformation gci;
StoreContactInformation sci;
XMLPhoneBook()
{
gci = new GetContactInformation();
}
/**
*
* getContactInfo function triggers the functions getFirstName, getLastName, getPhoneNumber of the GetContactInformation class.
*/
void getContactInfo(){
gci.getFirstName();
gci.getLastName();
gci.getPhoneNumber();
}
/**
*
* The variables FName, LName, PhoneNumber of the class GetContactInformation contains the user entered data, these values are passed to the class StoreContactInformation for creating/updating an XML file with user data.
*/
void storeContactInfo(){
sci = new StoreContactInformation(gci.FName,gci.LName,gci.PhoneNumber);
}
public static void main(String[] args)
{
XMLPhoneBook pb = new XMLPhoneBook();
pb.getContactInfo();
pb.storeContactInfo();
}
}
/**
*
* Class GetContactInformation is responsible for getting inputs from the user such as First Name, Last Name and Phone Number.
* The variables FName(String), LName(String), PhoneNumber(long) are used for containing the user data during run time.
* The Variable reader(Scanner) is used for getting inputs from the user via the console.
*/
import java.util.Scanner;
public class GetContactInformation {
String FName;
String LName;
long PhoneNumber;
Scanner reader;
GetContactInformation(){
FName=null;
LName=null;
PhoneNumber=0;
}
/**
*
* The function getFirstName prompts the user for this first name and gets the inputs from the console.
* Then the value for the first name is passed to the function setFirstName.
*/
void getFirstName(){
System.out.println("Enter Your FirstName = ");
reader = new Scanner(System.in);
setFirstName(reader.nextLine());
}
/**
*
* The function getLastName prompts the user for this last name and gets the inputs from the console.
* Then the value for the last name is passed to the function setLastName.
*/
void getLastName(){
System.out.println("Enter Your LastName = ");
reader = new Scanner(System.in);
setLastName(reader.nextLine());
}
/**
*
* The function getPhoneNumber prompts the user for this phone number and gets the inputs from the console.
* Then the value for the phone number is passed to the function setPhoneNumber.
*/
void getPhoneNumber(){
try{
System.out.println("Enter Your PhoneNumber = ");
reader = new Scanner(System.in);
setPhoneNumber(Long.parseUnsignedLong(reader.nextLine()));
}catch(java.lang.NumberFormatException e){
}
}
/**
*
* The function setFirstName assigns the value it receives to the variable FName.
*/
String setFirstName(String FN){
return FName=FN;
}
/**
*
* The function setLastName assigns the value it receives to the variable LName.
*/
String setLastName(String LN){
return LName=LN;
}
/**
*
* The function setPhoneNumber assigns the value it receives to the variable PhoneNumber.
*/
long setPhoneNumber(long PN){
return PhoneNumber=PN;
}
}
/**
*
* The StoreContactInformation is responsible for storing the user data such as first name, last name and phone number into an XML file called PhoneBook.xml.
* The StoreContactInformation first checks if the XML file already exist then if the file exist it simply updates the file or else creates a new XML file with the provided user data.
*
*/
import java.io.File;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.OutputKeys;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.xml.sax.SAXException;
import java.io.IOException;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
public class StoreContactInformation {
File f;
String filePathString ;
DocumentBuilderFactory docFactory ;
DocumentBuilder docBuilder ;
Document doc;
TransformerFactory transformerFactory;
Transformer transformer;
DOMSource source;
StreamResult result;
String FirstName;
String LastName;
long PhoneNumber;
StoreContactInformation(String fn, String ln, long pn){
filePathString="PhoneBook.xml"; //File Path is the current working directory.
f = new File(filePathString);
FirstName=fn;
LastName=ln;
PhoneNumber=pn;
docFactory = DocumentBuilderFactory.newInstance();
try {
docBuilder = docFactory.newDocumentBuilder();
}
catch (ParserConfigurationException pce)
{
pce.printStackTrace();
}
transformerFactory = TransformerFactory.newInstance();
try
{
transformer = transformerFactory.newTransformer();
}
catch (TransformerException tfe)
{
tfe.printStackTrace();
}
// check if the XML file exist already !
if(f.exists() && !f.isDirectory()) {
//if exist
UpdateXMLFile();
WriteToXMLFile();
}else{
//if do not exist
CreateXMLFile();
WriteToXMLFile();
}
}
/**
*
* The function CreateXMLFile creates a new XML file if one doesn't exist already.
* The first set of data stored in the XML file is given the unique id="1".
* The root element of the XML file is "ContactInformation" which contains child nodes "Contact" with there unique ids.
* The element "contact further contains child nodes "FirstName","LastName" and "PhoneNumber".
*/
void CreateXMLFile(){
doc = docBuilder.newDocument();
Element rootElement = doc.createElement("ContactInformation");
doc.appendChild(rootElement);
Element contact = doc.createElement("Contact");
rootElement.appendChild(contact);
Attr attr = doc.createAttribute("id");
attr.setValue("1");
contact.setAttributeNode(attr);
Element firstname = doc.createElement("FirstName");
firstname.appendChild(doc.createTextNode(FirstName));
contact.appendChild(firstname);
Element lastname = doc.createElement("LastName");
lastname.appendChild(doc.createTextNode(LastName));
contact.appendChild(lastname);
Element PN = doc.createElement("PhoneNumber");
PN.appendChild(doc.createTextNode(java.lang.Long.toString(PhoneNumber)));
contact.appendChild(PN);
}
/**
*
* The function WriteToXMLFile is responsible for writing the data into output XML file "PhoneBook.xml".
* WriteToXMLFile also formats the data to be written into pretty print way with INDENT spaces and line breaks etc.
*/
void WriteToXMLFile(){
try
{
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
source = new DOMSource(doc);
result = new StreamResult(new File(filePathString));
transformer.transform(source, result);
System.out.println("Contact Saved !");
}
catch (TransformerException tfe)
{
tfe.printStackTrace();
}
}
/**
*
* The function UpdateXMLFile updates the existing XML file with the new user data.
* The new set of user data gets a unique id for the element "Contact" which is calculated and generated by UpdateXMLFile.
*
*/
void UpdateXMLFile(){
try
{
doc = docBuilder.parse(filePathString);
}catch(SAXException sae){
}catch (IOException ioe) {
ioe.printStackTrace();
}
int AttrValue=1;
Node ContactInfo = doc.getFirstChild();
NodeList NumberChildNodes = ContactInfo.getChildNodes();
for(int i=0;i<NumberChildNodes.getLength();i++)
{
Node n = NumberChildNodes.item(i);
if ("Contact".equals(n.getNodeName()))
{
AttrValue+=1;
}
}
Element contact = doc.createElement("Contact");
ContactInfo.appendChild(contact);
Attr attr = doc.createAttribute("id");
attr.setValue(Integer.toString(AttrValue));
contact.setAttributeNode(attr);
Element firstname = doc.createElement("FirstName");
firstname.appendChild(doc.createTextNode(FirstName));
contact.appendChild(firstname);
Element lastname = doc.createElement("LastName");
lastname.appendChild(doc.createTextNode(LastName));
contact.appendChild(lastname);
Element PN = doc.createElement("PhoneNumber");
PN.appendChild(doc.createTextNode(java.lang.Long.toString(PhoneNumber)));
contact.appendChild(PN);
}
}
/**
*
* @author Sanjayan Ravi
*/
/**
*
* Class XMLPhoneBook is the Main Class that controls getContactInfo function and storeContactInfo.
*/
public class XMLPhoneBook
{
GetContactInformation gci;
StoreContactInformation sci;
XMLPhoneBook()
{
gci = new GetContactInformation();
}
/**
*
* getContactInfo function triggers the functions getFirstName, getLastName, getPhoneNumber of the GetContactInformation class.
*/
void getContactInfo(){
gci.getFirstName();
gci.getLastName();
gci.getPhoneNumber();
}
/**
*
* The variables FName, LName, PhoneNumber of the class GetContactInformation contains the user entered data, these values are passed to the class StoreContactInformation for creating/updating an XML file with user data.
*/
void storeContactInfo(){
sci = new StoreContactInformation(gci.FName,gci.LName,gci.PhoneNumber);
}
public static void main(String[] args)
{
XMLPhoneBook pb = new XMLPhoneBook();
pb.getContactInfo();
pb.storeContactInfo();
}
}
/**
*
* Class GetContactInformation is responsible for getting inputs from the user such as First Name, Last Name and Phone Number.
* The variables FName(String), LName(String), PhoneNumber(long) are used for containing the user data during run time.
* The Variable reader(Scanner) is used for getting inputs from the user via the console.
*/
import java.util.Scanner;
public class GetContactInformation {
String FName;
String LName;
long PhoneNumber;
Scanner reader;
GetContactInformation(){
FName=null;
LName=null;
PhoneNumber=0;
}
/**
*
* The function getFirstName prompts the user for this first name and gets the inputs from the console.
* Then the value for the first name is passed to the function setFirstName.
*/
void getFirstName(){
System.out.println("Enter Your FirstName = ");
reader = new Scanner(System.in);
setFirstName(reader.nextLine());
}
/**
*
* The function getLastName prompts the user for this last name and gets the inputs from the console.
* Then the value for the last name is passed to the function setLastName.
*/
void getLastName(){
System.out.println("Enter Your LastName = ");
reader = new Scanner(System.in);
setLastName(reader.nextLine());
}
/**
*
* The function getPhoneNumber prompts the user for this phone number and gets the inputs from the console.
* Then the value for the phone number is passed to the function setPhoneNumber.
*/
void getPhoneNumber(){
try{
System.out.println("Enter Your PhoneNumber = ");
reader = new Scanner(System.in);
setPhoneNumber(Long.parseUnsignedLong(reader.nextLine()));
}catch(java.lang.NumberFormatException e){
}
}
/**
*
* The function setFirstName assigns the value it receives to the variable FName.
*/
String setFirstName(String FN){
return FName=FN;
}
/**
*
* The function setLastName assigns the value it receives to the variable LName.
*/
String setLastName(String LN){
return LName=LN;
}
/**
*
* The function setPhoneNumber assigns the value it receives to the variable PhoneNumber.
*/
long setPhoneNumber(long PN){
return PhoneNumber=PN;
}
}
/**
*
* The StoreContactInformation is responsible for storing the user data such as first name, last name and phone number into an XML file called PhoneBook.xml.
* The StoreContactInformation first checks if the XML file already exist then if the file exist it simply updates the file or else creates a new XML file with the provided user data.
*
*/
import java.io.File;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.OutputKeys;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.xml.sax.SAXException;
import java.io.IOException;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
public class StoreContactInformation {
File f;
String filePathString ;
DocumentBuilderFactory docFactory ;
DocumentBuilder docBuilder ;
Document doc;
TransformerFactory transformerFactory;
Transformer transformer;
DOMSource source;
StreamResult result;
String FirstName;
String LastName;
long PhoneNumber;
StoreContactInformation(String fn, String ln, long pn){
filePathString="PhoneBook.xml"; //File Path is the current working directory.
f = new File(filePathString);
FirstName=fn;
LastName=ln;
PhoneNumber=pn;
docFactory = DocumentBuilderFactory.newInstance();
try {
docBuilder = docFactory.newDocumentBuilder();
}
catch (ParserConfigurationException pce)
{
pce.printStackTrace();
}
transformerFactory = TransformerFactory.newInstance();
try
{
transformer = transformerFactory.newTransformer();
}
catch (TransformerException tfe)
{
tfe.printStackTrace();
}
// check if the XML file exist already !
if(f.exists() && !f.isDirectory()) {
//if exist
UpdateXMLFile();
WriteToXMLFile();
}else{
//if do not exist
CreateXMLFile();
WriteToXMLFile();
}
}
/**
*
* The function CreateXMLFile creates a new XML file if one doesn't exist already.
* The first set of data stored in the XML file is given the unique id="1".
* The root element of the XML file is "ContactInformation" which contains child nodes "Contact" with there unique ids.
* The element "contact further contains child nodes "FirstName","LastName" and "PhoneNumber".
*/
void CreateXMLFile(){
doc = docBuilder.newDocument();
Element rootElement = doc.createElement("ContactInformation");
doc.appendChild(rootElement);
Element contact = doc.createElement("Contact");
rootElement.appendChild(contact);
Attr attr = doc.createAttribute("id");
attr.setValue("1");
contact.setAttributeNode(attr);
Element firstname = doc.createElement("FirstName");
firstname.appendChild(doc.createTextNode(FirstName));
contact.appendChild(firstname);
Element lastname = doc.createElement("LastName");
lastname.appendChild(doc.createTextNode(LastName));
contact.appendChild(lastname);
Element PN = doc.createElement("PhoneNumber");
PN.appendChild(doc.createTextNode(java.lang.Long.toString(PhoneNumber)));
contact.appendChild(PN);
}
/**
*
* The function WriteToXMLFile is responsible for writing the data into output XML file "PhoneBook.xml".
* WriteToXMLFile also formats the data to be written into pretty print way with INDENT spaces and line breaks etc.
*/
void WriteToXMLFile(){
try
{
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
source = new DOMSource(doc);
result = new StreamResult(new File(filePathString));
transformer.transform(source, result);
System.out.println("Contact Saved !");
}
catch (TransformerException tfe)
{
tfe.printStackTrace();
}
}
/**
*
* The function UpdateXMLFile updates the existing XML file with the new user data.
* The new set of user data gets a unique id for the element "Contact" which is calculated and generated by UpdateXMLFile.
*
*/
void UpdateXMLFile(){
try
{
doc = docBuilder.parse(filePathString);
}catch(SAXException sae){
}catch (IOException ioe) {
ioe.printStackTrace();
}
int AttrValue=1;
Node ContactInfo = doc.getFirstChild();
NodeList NumberChildNodes = ContactInfo.getChildNodes();
for(int i=0;i<NumberChildNodes.getLength();i++)
{
Node n = NumberChildNodes.item(i);
if ("Contact".equals(n.getNodeName()))
{
AttrValue+=1;
}
}
Element contact = doc.createElement("Contact");
ContactInfo.appendChild(contact);
Attr attr = doc.createAttribute("id");
attr.setValue(Integer.toString(AttrValue));
contact.setAttributeNode(attr);
Element firstname = doc.createElement("FirstName");
firstname.appendChild(doc.createTextNode(FirstName));
contact.appendChild(firstname);
Element lastname = doc.createElement("LastName");
lastname.appendChild(doc.createTextNode(LastName));
contact.appendChild(lastname);
Element PN = doc.createElement("PhoneNumber");
PN.appendChild(doc.createTextNode(java.lang.Long.toString(PhoneNumber)));
contact.appendChild(PN);
}
}
C:\Users\xxxxxx\Documents\Java\xml>java XMLPhoneBook
Enter Your FirstName =
XXXXXX
Enter Your LastName =
YYYYYY
Enter Your PhoneNumber =
789634569863
Contact Saved !
/**
*
* @author Sanjayan Ravi
*/
package xmlphonebook;
/**
*
* Class XMLPhoneBook is the Main Class that controls getContactInfo function and storeContactInfo.
*/
public class XMLPhoneBook
{
GetContactInformation gci;
StoreContactInformation sci;
XMLPhoneBook()
{
gci = new GetContactInformation();
}
/**
*
* getContactInfo function triggers the functions getFirstName, getLastName, getPhoneNumber of the GetContactInformation class.
*/
void getContactInfo()throws Exception {
gci.getFirstName();
gci.getLastName();
gci.getPhoneNumber();
}
/**
*
* The variables FName, LName, PhoneNumber of the class GetContactInformation contains the user entered data, these values are passed to the class StoreContactInformation for creating/updating an XML file with user data.
*/
void storeContactInfo()throws Exception{
sci = new StoreContactInformation(gci.FName,gci.LName,gci.PhoneNumber);
}
public static void main(String[] args)
{
XMLPhoneBook pb = new XMLPhoneBook();
try{
pb.getContactInfo();
pb.storeContactInfo();
}catch(Exception e){
ErrorHandler er = new ErrorHandler(e);
}
}
}
package xmlphonebook;
/**
*
* Class GetContactInformation is responsible for getting inputs from the user such as First Name, Last Name and Phone Number.
* The variables FName(String), LName(String), PhoneNumber(long) are used for containing the user data during run time.
* The Variable reader(Scanner) is used for getting inputs from the user via the console.
*/
import java.util.Scanner;
public class GetContactInformation {
String FName;
String LName;
long PhoneNumber;
Scanner reader;
GetContactInformation(){
FName=null;
LName=null;
PhoneNumber=0;
}
/**
*
* The function getFirstName prompts the user for this first name and gets the inputs from the console.
* Then the value for the first name is passed to the function setFirstName.
*/
void getFirstName()throws Exception{
System.out.println("Enter Your FirstName = ");
reader = new Scanner(System.in);
setFirstName(reader.nextLine());
}
/**
*
* The function getLastName prompts the user for this last name and gets the inputs from the console.
* Then the value for the last name is passed to the function setLastName.
*/
void getLastName()throws Exception{
System.out.println("Enter Your LastName = ");
reader = new Scanner(System.in);
setLastName(reader.nextLine());
}
/**
*
* The function getPhoneNumber prompts the user for this phone number and gets the inputs from the console.
* Then the value for the phone number is passed to the function setPhoneNumber.
*/
void getPhoneNumber()throws Exception{
System.out.println("Enter Your PhoneNumber = ");
reader = new Scanner(System.in);
setPhoneNumber(Long.parseUnsignedLong(reader.nextLine()));
}
/**
*
* The function setFirstName assigns the value it receives to the variable FName.
*/
String setFirstName(String FN)throws Exception{
return FName=FN;
}
/**
*
* The function setLastName assigns the value it receives to the variable LName.
*/
String setLastName(String LN)throws Exception{
return LName=LN;
}
/**
*
* The function setPhoneNumber assigns the value it receives to the variable PhoneNumber.
*/
long setPhoneNumber(long PN)throws Exception{
return PhoneNumber=PN;
}
}
package xmlphonebook;
/**
*
* The StoreContactInformation is responsible for storing the user data such as first name, last name and phone number into an XML file called PhoneBook.xml.
* The StoreContactInformation first checks if the XML file already exist then if the file exist it simply updates the file or else creates a new XML file with the provided user data.
*
*/
import java.io.File;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.TransformerException;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import java.util.Scanner;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
public class StoreContactInformation {
File f;
String filePathString ;
DocumentBuilderFactory docFactory ;
DocumentBuilder docBuilder ;
Document doc;
TransformerFactory transformerFactory;
Transformer transformer;
DOMSource source;
StreamResult result;
String FirstName;
String LastName;
long PhoneNumber;
int choice;
Scanner reader;
OutputKeys OutputKeys;
StoreContactInformation(String fn, String ln, long pn) throws Exception {
filePathString="PhoneBook.xml"; //File Path is the current working directory.
f = new File(filePathString);
FirstName=fn;
LastName=ln;
PhoneNumber=pn;
docFactory = DocumentBuilderFactory.newInstance();
docBuilder = docFactory.newDocumentBuilder();
transformerFactory = TransformerFactory.newInstance();
// check if the XML file exist already !
if(f.exists() && !f.isDirectory()) {
//if exist
UpdateXMLFile();
WriteToXMLFile();
}else{
//if do not exist
CreateXMLFile();
WriteToXMLFile();
}
}
/**
*
* The function CreateXMLFile creates a new XML file if one doesn't exist already.
* The first set of data stored in the XML file is given the unique id="1".
* The root element of the XML file is "ContactInformation" which contains child nodes "Contact" with there unique ids.
* The element "contact further contains child nodes "FirstName","LastName" and "PhoneNumber".
*/
void CreateXMLFile(){
doc = docBuilder.newDocument();
Element rootElement = doc.createElement("ContactInformation");
doc.appendChild(rootElement);
Element contact = doc.createElement("Contact");
rootElement.appendChild(contact);
Attr attr = doc.createAttribute("id");
attr.setValue("1");
contact.setAttributeNode(attr);
Element firstname = doc.createElement("FirstName");
firstname.appendChild(doc.createTextNode(FirstName));
contact.appendChild(firstname);
Element lastname = doc.createElement("LastName");
lastname.appendChild(doc.createTextNode(LastName));
contact.appendChild(lastname);
Element PN = doc.createElement("PhoneNumber");
PN.appendChild(doc.createTextNode(java.lang.Long.toString(PhoneNumber)));
contact.appendChild(PN);
}
/**
*
* The function WriteToXMLFile is responsible for writing the data into output XML file "PhoneBook.xml".
* WriteToXMLFile also formats the data to be written into pretty print way with INDENT spaces and line breaks etc.
*/
void WriteToXMLFile() throws Exception{
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
source = new DOMSource(doc);
result = new StreamResult(new File(filePathString));
transformer.transform(source, result);
System.out.println("Contact Saved !");
}
/**
*
* The function UpdateXMLFile updates the existing XML file with the new user data.
* The new set of user data gets a unique id for the element "Contact" which is calculated and generated by UpdateXMLFile.
*
*/
void UpdateXMLFile() throws Exception{
doc = docBuilder.parse(filePathString);
int AttrValue=1;
Node ContactInfo = doc.getFirstChild();
NodeList NumberChildNodes = ContactInfo.getChildNodes();
for(int i=0;i<NumberChildNodes.getLength();i++)
{
Node n = NumberChildNodes.item(i);
if ("Contact".equals(n.getNodeName()))
{
AttrValue+=1;
}
}
Element contact = doc.createElement("Contact");
ContactInfo.appendChild(contact);
Attr attr = doc.createAttribute("id");
attr.setValue(Integer.toString(AttrValue));
contact.setAttributeNode(attr);
Element firstname = doc.createElement("FirstName");
firstname.appendChild(doc.createTextNode(FirstName));
contact.appendChild(firstname);
Element lastname = doc.createElement("LastName");
lastname.appendChild(doc.createTextNode(LastName));
contact.appendChild(lastname);
Element PN = doc.createElement("PhoneNumber");
PN.appendChild(doc.createTextNode(java.lang.Long.toString(PhoneNumber)));
contact.appendChild(PN);
}
}
Enter Your FirstName =
xxxxxxxx
Enter Your LastName =
yyyyyyyy
Enter Your PhoneNumber =
7896456123693
void WriteToXMLFile() throws Exception{
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
source = new DOMSource(doc);
result = new StreamResult(new File(filePathString));
transformer.transform(source, result);
System.out.println("Contact Saved !");
}
C:\Users\xxxxxx\Documents\Java\xml>java XMLPhoneBook
Enter Your FirstName =
XXXXXX
Enter Your LastName =
YYYYYY
Enter Your PhoneNumber =
789634569863
Contact Saved !
/**
*
* @author Sanjayan Ravi
*/
package xmlphonebook;
/**
*
* Class XMLPhoneBook is the Main Class that controls getContactInfo function and storeContactInfo.
*/
public class XMLPhoneBook
{
GetContactInformation gci;
StoreContactInformation sci;
XMLPhoneBook()
{
gci = new GetContactInformation();
}
/**
*
* getContactInfo function triggers the functions getFirstName, getLastName, getPhoneNumber of the GetContactInformation class.
*/
void getContactInfo()throws Exception {
gci.getFirstName();
gci.getLastName();
gci.getPhoneNumber();
}
/**
*
* The variables FName, LName, PhoneNumber of the class GetContactInformation contains the user entered data, these values are passed to the class StoreContactInformation for creating/updating an XML file with user data.
*/
void storeContactInfo()throws Exception{
sci = new StoreContactInformation(gci.FName,gci.LName,gci.PhoneNumber);
}
public static void main(String[] args)
{
XMLPhoneBook pb = new XMLPhoneBook();
try{
pb.getContactInfo();
pb.storeContactInfo();
}catch(Exception e){
ErrorHandler er = new ErrorHandler(e);
}
}
}
package xmlphonebook;
/**
*
* Class GetContactInformation is responsible for getting inputs from the user such as First Name, Last Name and Phone Number.
* The variables FName(String), LName(String), PhoneNumber(long) are used for containing the user data during run time.
* The Variable reader(Scanner) is used for getting inputs from the user via the console.
*/
import java.util.Scanner;
public class GetContactInformation {
String FName;
String LName;
long PhoneNumber;
Scanner reader;
GetContactInformation(){
FName=null;
LName=null;
PhoneNumber=0;
}
/**
*
* The function getFirstName prompts the user for this first name and gets the inputs from the console.
* Then the value for the first name is passed to the function setFirstName.
*/
void getFirstName()throws Exception{
System.out.println("Enter Your FirstName = ");
reader = new Scanner(System.in);
setFirstName(reader.nextLine());
}
/**
*
* The function getLastName prompts the user for this last name and gets the inputs from the console.
* Then the value for the last name is passed to the function setLastName.
*/
void getLastName()throws Exception{
System.out.println("Enter Your LastName = ");
reader = new Scanner(System.in);
setLastName(reader.nextLine());
}
/**
*
* The function getPhoneNumber prompts the user for this phone number and gets the inputs from the console.
* Then the value for the phone number is passed to the function setPhoneNumber.
*/
void getPhoneNumber()throws Exception{
System.out.println("Enter Your PhoneNumber = ");
reader = new Scanner(System.in);
setPhoneNumber(Long.parseUnsignedLong(reader.nextLine()));
}
/**
*
* The function setFirstName assigns the value it receives to the variable FName.
*/
String setFirstName(String FN)throws Exception{
return FName=FN;
}
/**
*
* The function setLastName assigns the value it receives to the variable LName.
*/
String setLastName(String LN)throws Exception{
return LName=LN;
}
/**
*
* The function setPhoneNumber assigns the value it receives to the variable PhoneNumber.
*/
long setPhoneNumber(long PN)throws Exception{
return PhoneNumber=PN;
}
}
package xmlphonebook;
/**
*
* The StoreContactInformation is responsible for storing the user data such as first name, last name and phone number into an XML file called PhoneBook.xml.
* The StoreContactInformation first checks if the XML file already exist then if the file exist it simply updates the file or else creates a new XML file with the provided user data.
*
*/
import java.io.File;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.TransformerException;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import java.util.Scanner;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
public class StoreContactInformation {
File f;
String filePathString ;
DocumentBuilderFactory docFactory ;
DocumentBuilder docBuilder ;
Document doc;
TransformerFactory transformerFactory;
Transformer transformer;
DOMSource source;
StreamResult result;
String FirstName;
String LastName;
long PhoneNumber;
int choice;
Scanner reader;
OutputKeys OutputKeys;
StoreContactInformation(String fn, String ln, long pn) throws Exception {
filePathString="PhoneBook.xml"; //File Path is the current working directory.
f = new File(filePathString);
FirstName=fn;
LastName=ln;
PhoneNumber=pn;
docFactory = DocumentBuilderFactory.newInstance();
docBuilder = docFactory.newDocumentBuilder();
transformerFactory = TransformerFactory.newInstance();
// check if the XML file exist already !
if(f.exists() && !f.isDirectory()) {
//if exist
UpdateXMLFile();
WriteToXMLFile();
}else{
//if do not exist
CreateXMLFile();
WriteToXMLFile();
}
}
/**
*
* The function CreateXMLFile creates a new XML file if one doesn't exist already.
* The first set of data stored in the XML file is given the unique id="1".
* The root element of the XML file is "ContactInformation" which contains child nodes "Contact" with there unique ids.
* The element "contact further contains child nodes "FirstName","LastName" and "PhoneNumber".
*/
void CreateXMLFile(){
doc = docBuilder.newDocument();
Element rootElement = doc.createElement("ContactInformation");
doc.appendChild(rootElement);
Element contact = doc.createElement("Contact");
rootElement.appendChild(contact);
Attr attr = doc.createAttribute("id");
attr.setValue("1");
contact.setAttributeNode(attr);
Element firstname = doc.createElement("FirstName");
firstname.appendChild(doc.createTextNode(FirstName));
contact.appendChild(firstname);
Element lastname = doc.createElement("LastName");
lastname.appendChild(doc.createTextNode(LastName));
contact.appendChild(lastname);
Element PN = doc.createElement("PhoneNumber");
PN.appendChild(doc.createTextNode(java.lang.Long.toString(PhoneNumber)));
contact.appendChild(PN);
}
/**
*
* The function WriteToXMLFile is responsible for writing the data into output XML file "PhoneBook.xml".
* WriteToXMLFile also formats the data to be written into pretty print way with INDENT spaces and line breaks etc.
*/
void WriteToXMLFile() throws Exception{
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
source = new DOMSource(doc);
result = new StreamResult(new File(filePathString));
transformer.transform(source, result);
System.out.println("Contact Saved !");
}
/**
*
* The function UpdateXMLFile updates the existing XML file with the new user data.
* The new set of user data gets a unique id for the element "Contact" which is calculated and generated by UpdateXMLFile.
*
*/
void UpdateXMLFile() throws Exception{
doc = docBuilder.parse(filePathString);
int AttrValue=1;
Node ContactInfo = doc.getFirstChild();
NodeList NumberChildNodes = ContactInfo.getChildNodes();
for(int i=0;i<NumberChildNodes.getLength();i++)
{
Node n = NumberChildNodes.item(i);
if ("Contact".equals(n.getNodeName()))
{
AttrValue+=1;
}
}
Element contact = doc.createElement("Contact");
ContactInfo.appendChild(contact);
Attr attr = doc.createAttribute("id");
attr.setValue(Integer.toString(AttrValue));
contact.setAttributeNode(attr);
Element firstname = doc.createElement("FirstName");
firstname.appendChild(doc.createTextNode(FirstName));
contact.appendChild(firstname);
Element lastname = doc.createElement("LastName");
lastname.appendChild(doc.createTextNode(LastName));
contact.appendChild(lastname);
Element PN = doc.createElement("PhoneNumber");
PN.appendChild(doc.createTextNode(java.lang.Long.toString(PhoneNumber)));
contact.appendChild(PN);
}
}
Enter Your FirstName =
xxxxxxxx
Enter Your LastName =
yyyyyyyy
Enter Your PhoneNumber =
7896456123693
void WriteToXMLFile() throws Exception{
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
source = new DOMSource(doc);
result = new StreamResult(new File(filePathString));
transformer.transform(source, result);
System.out.println("Contact Saved !");
}
C:\Users\xxxxxx\Documents\Java\xml>java XMLPhoneBook
Enter Your FirstName =
XXXXXX
Enter Your LastName =
YYYYYY
Enter Your PhoneNumber =
789634569863
Contact Saved !
/**
*
* @author Sanjayan Ravi
*/
package xmlphonebook;
/**
*
* Class XMLPhoneBook is the Main Class that controls getContactInfo function and storeContactInfo.
*/
public class XMLPhoneBook
{
GetContactInformation gci;
StoreContactInformation sci;
XMLPhoneBook()
{
gci = new GetContactInformation();
}
/**
*
* getContactInfo function triggers the functions getFirstName, getLastName, getPhoneNumber of the GetContactInformation class.
*/
void getContactInfo()throws Exception {
gci.getFirstName();
gci.getLastName();
gci.getPhoneNumber();
}
/**
*
* The variables FName, LName, PhoneNumber of the class GetContactInformation contains the user entered data, these values are passed to the class StoreContactInformation for creating/updating an XML file with user data.
*/
void storeContactInfo()throws Exception{
sci = new StoreContactInformation(gci.FName,gci.LName,gci.PhoneNumber);
}
public static void main(String[] args)
{
XMLPhoneBook pb = new XMLPhoneBook();
try{
pb.getContactInfo();
pb.storeContactInfo();
}catch(Exception e){
ErrorHandler er = new ErrorHandler(e);
}
}
}
package xmlphonebook;
/**
*
* Class GetContactInformation is responsible for getting inputs from the user such as First Name, Last Name and Phone Number.
* The variables FName(String), LName(String), PhoneNumber(long) are used for containing the user data during run time.
* The Variable reader(Scanner) is used for getting inputs from the user via the console.
*/
import java.util.Scanner;
public class GetContactInformation {
String FName;
String LName;
long PhoneNumber;
Scanner reader;
GetContactInformation(){
FName=null;
LName=null;
PhoneNumber=0;
}
/**
*
* The function getFirstName prompts the user for this first name and gets the inputs from the console.
* Then the value for the first name is passed to the function setFirstName.
*/
void getFirstName()throws Exception{
System.out.println("Enter Your FirstName = ");
reader = new Scanner(System.in);
setFirstName(reader.nextLine());
}
/**
*
* The function getLastName prompts the user for this last name and gets the inputs from the console.
* Then the value for the last name is passed to the function setLastName.
*/
void getLastName()throws Exception{
System.out.println("Enter Your LastName = ");
reader = new Scanner(System.in);
setLastName(reader.nextLine());
}
/**
*
* The function getPhoneNumber prompts the user for this phone number and gets the inputs from the console.
* Then the value for the phone number is passed to the function setPhoneNumber.
*/
void getPhoneNumber()throws Exception{
System.out.println("Enter Your PhoneNumber = ");
reader = new Scanner(System.in);
setPhoneNumber(Long.parseUnsignedLong(reader.nextLine()));
}
/**
*
* The function setFirstName assigns the value it receives to the variable FName.
*/
String setFirstName(String FN)throws Exception{
return FName=FN;
}
/**
*
* The function setLastName assigns the value it receives to the variable LName.
*/
String setLastName(String LN)throws Exception{
return LName=LN;
}
/**
*
* The function setPhoneNumber assigns the value it receives to the variable PhoneNumber.
*/
long setPhoneNumber(long PN)throws Exception{
return PhoneNumber=PN;
}
}
package xmlphonebook;
/**
*
* The StoreContactInformation is responsible for storing the user data such as first name, last name and phone number into an XML file called PhoneBook.xml.
* The StoreContactInformation first checks if the XML file already exist then if the file exist it simply updates the file or else creates a new XML file with the provided user data.
*
*/
import java.io.File;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.TransformerException;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import java.util.Scanner;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
public class StoreContactInformation {
File f;
String filePathString ;
DocumentBuilderFactory docFactory ;
DocumentBuilder docBuilder ;
Document doc;
TransformerFactory transformerFactory;
Transformer transformer;
DOMSource source;
StreamResult result;
String FirstName;
String LastName;
long PhoneNumber;
int choice;
Scanner reader;
OutputKeys OutputKeys;
StoreContactInformation(String fn, String ln, long pn) throws Exception {
filePathString="PhoneBook.xml"; //File Path is the current working directory.
f = new File(filePathString);
FirstName=fn;
LastName=ln;
PhoneNumber=pn;
docFactory = DocumentBuilderFactory.newInstance();
docBuilder = docFactory.newDocumentBuilder();
transformerFactory = TransformerFactory.newInstance();
// check if the XML file exist already !
if(f.exists() && !f.isDirectory()) {
//if exist
UpdateXMLFile();
WriteToXMLFile();
}else{
//if do not exist
CreateXMLFile();
WriteToXMLFile();
}
}
/**
*
* The function CreateXMLFile creates a new XML file if one doesn't exist already.
* The first set of data stored in the XML file is given the unique id="1".
* The root element of the XML file is "ContactInformation" which contains child nodes "Contact" with there unique ids.
* The element "contact further contains child nodes "FirstName","LastName" and "PhoneNumber".
*/
void CreateXMLFile(){
doc = docBuilder.newDocument();
Element rootElement = doc.createElement("ContactInformation");
doc.appendChild(rootElement);
Element contact = doc.createElement("Contact");
rootElement.appendChild(contact);
Attr attr = doc.createAttribute("id");
attr.setValue("1");
contact.setAttributeNode(attr);
Element firstname = doc.createElement("FirstName");
firstname.appendChild(doc.createTextNode(FirstName));
contact.appendChild(firstname);
Element lastname = doc.createElement("LastName");
lastname.appendChild(doc.createTextNode(LastName));
contact.appendChild(lastname);
Element PN = doc.createElement("PhoneNumber");
PN.appendChild(doc.createTextNode(java.lang.Long.toString(PhoneNumber)));
contact.appendChild(PN);
}
/**
*
* The function WriteToXMLFile is responsible for writing the data into output XML file "PhoneBook.xml".
* WriteToXMLFile also formats the data to be written into pretty print way with INDENT spaces and line breaks etc.
*/
void WriteToXMLFile() throws Exception{
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
source = new DOMSource(doc);
result = new StreamResult(new File(filePathString));
transformer.transform(source, result);
System.out.println("Contact Saved !");
}
/**
*
* The function UpdateXMLFile updates the existing XML file with the new user data.
* The new set of user data gets a unique id for the element "Contact" which is calculated and generated by UpdateXMLFile.
*
*/
void UpdateXMLFile() throws Exception{
doc = docBuilder.parse(filePathString);
int AttrValue=1;
Node ContactInfo = doc.getFirstChild();
NodeList NumberChildNodes = ContactInfo.getChildNodes();
for(int i=0;i<NumberChildNodes.getLength();i++)
{
Node n = NumberChildNodes.item(i);
if ("Contact".equals(n.getNodeName()))
{
AttrValue+=1;
}
}
Element contact = doc.createElement("Contact");
ContactInfo.appendChild(contact);
Attr attr = doc.createAttribute("id");
attr.setValue(Integer.toString(AttrValue));
contact.setAttributeNode(attr);
Element firstname = doc.createElement("FirstName");
firstname.appendChild(doc.createTextNode(FirstName));
contact.appendChild(firstname);
Element lastname = doc.createElement("LastName");
lastname.appendChild(doc.createTextNode(LastName));
contact.appendChild(lastname);
Element PN = doc.createElement("PhoneNumber");
PN.appendChild(doc.createTextNode(java.lang.Long.toString(PhoneNumber)));
contact.appendChild(PN);
}
}
Enter Your FirstName =
xxxxxxxx
Enter Your LastName =
yyyyyyyy
Enter Your PhoneNumber =
7896456123693
void WriteToXMLFile() throws Exception{
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
source = new DOMSource(doc);
result = new StreamResult(new File(filePathString));
transformer.transform(source, result);
System.out.println("Contact Saved !");
}
C:\Users\xxxxxx\Documents\Java\xml>java XMLPhoneBook
Enter Your FirstName =
XXXXXX
Enter Your LastName =
YYYYYY
Enter Your PhoneNumber =
789634569863
Contact Saved !
/**
*
* @author Sanjayan Ravi
*/
package xmlphonebook;
/**
*
* Class XMLPhoneBook is the Main Class that controls getContactInfo function and storeContactInfo.
*/
public class XMLPhoneBook
{
GetContactInformation gci;
StoreContactInformation sci;
XMLPhoneBook()
{
gci = new GetContactInformation();
}
/**
*
* getContactInfo function triggers the functions getFirstName, getLastName, getPhoneNumber of the GetContactInformation class.
*/
void getContactInfo()throws Exception {
gci.getFirstName();
gci.getLastName();
gci.getPhoneNumber();
}
/**
*
* The variables FName, LName, PhoneNumber of the class GetContactInformation contains the user entered data, these values are passed to the class StoreContactInformation for creating/updating an XML file with user data.
*/
void storeContactInfo()throws Exception{
sci = new StoreContactInformation(gci.FName,gci.LName,gci.PhoneNumber);
}
public static void main(String[] args)
{
XMLPhoneBook pb = new XMLPhoneBook();
try{
pb.getContactInfo();
pb.storeContactInfo();
}catch(Exception e){
ErrorHandler er = new ErrorHandler(e);
}
}
}
package xmlphonebook;
/**
*
* Class GetContactInformation is responsible for getting inputs from the user such as First Name, Last Name and Phone Number.
* The variables FName(String), LName(String), PhoneNumber(long) are used for containing the user data during run time.
* The Variable reader(Scanner) is used for getting inputs from the user via the console.
*/
import java.util.Scanner;
public class GetContactInformation {
String FName;
String LName;
long PhoneNumber;
Scanner reader;
GetContactInformation(){
FName=null;
LName=null;
PhoneNumber=0;
}
/**
*
* The function getFirstName prompts the user for this first name and gets the inputs from the console.
* Then the value for the first name is passed to the function setFirstName.
*/
void getFirstName()throws Exception{
System.out.println("Enter Your FirstName = ");
reader = new Scanner(System.in);
setFirstName(reader.nextLine());
}
/**
*
* The function getLastName prompts the user for this last name and gets the inputs from the console.
* Then the value for the last name is passed to the function setLastName.
*/
void getLastName()throws Exception{
System.out.println("Enter Your LastName = ");
reader = new Scanner(System.in);
setLastName(reader.nextLine());
}
/**
*
* The function getPhoneNumber prompts the user for this phone number and gets the inputs from the console.
* Then the value for the phone number is passed to the function setPhoneNumber.
*/
void getPhoneNumber()throws Exception{
System.out.println("Enter Your PhoneNumber = ");
reader = new Scanner(System.in);
setPhoneNumber(Long.parseUnsignedLong(reader.nextLine()));
}
/**
*
* The function setFirstName assigns the value it receives to the variable FName.
*/
String setFirstName(String FN)throws Exception{
return FName=FN;
}
/**
*
* The function setLastName assigns the value it receives to the variable LName.
*/
String setLastName(String LN)throws Exception{
return LName=LN;
}
/**
*
* The function setPhoneNumber assigns the value it receives to the variable PhoneNumber.
*/
long setPhoneNumber(long PN)throws Exception{
return PhoneNumber=PN;
}
}
package xmlphonebook;
/**
*
* The StoreContactInformation is responsible for storing the user data such as first name, last name and phone number into an XML file called PhoneBook.xml.
* The StoreContactInformation first checks if the XML file already exist then if the file exist it simply updates the file or else creates a new XML file with the provided user data.
*
*/
import java.io.File;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.TransformerException;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import java.util.Scanner;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
public class StoreContactInformation {
File f;
String filePathString ;
DocumentBuilderFactory docFactory ;
DocumentBuilder docBuilder ;
Document doc;
TransformerFactory transformerFactory;
Transformer transformer;
DOMSource source;
StreamResult result;
String FirstName;
String LastName;
long PhoneNumber;
int choice;
Scanner reader;
OutputKeys OutputKeys;
StoreContactInformation(String fn, String ln, long pn) throws Exception {
filePathString="PhoneBook.xml"; //File Path is the current working directory.
f = new File(filePathString);
FirstName=fn;
LastName=ln;
PhoneNumber=pn;
docFactory = DocumentBuilderFactory.newInstance();
docBuilder = docFactory.newDocumentBuilder();
transformerFactory = TransformerFactory.newInstance();
// check if the XML file exist already !
if(f.exists() && !f.isDirectory()) {
//if exist
UpdateXMLFile();
WriteToXMLFile();
}else{
//if do not exist
CreateXMLFile();
WriteToXMLFile();
}
}
/**
*
* The function CreateXMLFile creates a new XML file if one doesn't exist already.
* The first set of data stored in the XML file is given the unique id="1".
* The root element of the XML file is "ContactInformation" which contains child nodes "Contact" with there unique ids.
* The element "contact further contains child nodes "FirstName","LastName" and "PhoneNumber".
*/
void CreateXMLFile(){
doc = docBuilder.newDocument();
Element rootElement = doc.createElement("ContactInformation");
doc.appendChild(rootElement);
Element contact = doc.createElement("Contact");
rootElement.appendChild(contact);
Attr attr = doc.createAttribute("id");
attr.setValue("1");
contact.setAttributeNode(attr);
Element firstname = doc.createElement("FirstName");
firstname.appendChild(doc.createTextNode(FirstName));
contact.appendChild(firstname);
Element lastname = doc.createElement("LastName");
lastname.appendChild(doc.createTextNode(LastName));
contact.appendChild(lastname);
Element PN = doc.createElement("PhoneNumber");
PN.appendChild(doc.createTextNode(java.lang.Long.toString(PhoneNumber)));
contact.appendChild(PN);
}
/**
*
* The function WriteToXMLFile is responsible for writing the data into output XML file "PhoneBook.xml".
* WriteToXMLFile also formats the data to be written into pretty print way with INDENT spaces and line breaks etc.
*/
void WriteToXMLFile() throws Exception{
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
source = new DOMSource(doc);
result = new StreamResult(new File(filePathString));
transformer.transform(source, result);
System.out.println("Contact Saved !");
}
/**
*
* The function UpdateXMLFile updates the existing XML file with the new user data.
* The new set of user data gets a unique id for the element "Contact" which is calculated and generated by UpdateXMLFile.
*
*/
void UpdateXMLFile() throws Exception{
doc = docBuilder.parse(filePathString);
int AttrValue=1;
Node ContactInfo = doc.getFirstChild();
NodeList NumberChildNodes = ContactInfo.getChildNodes();
for(int i=0;i<NumberChildNodes.getLength();i++)
{
Node n = NumberChildNodes.item(i);
if ("Contact".equals(n.getNodeName()))
{
AttrValue+=1;
}
}
Element contact = doc.createElement("Contact");
ContactInfo.appendChild(contact);
Attr attr = doc.createAttribute("id");
attr.setValue(Integer.toString(AttrValue));
contact.setAttributeNode(attr);
Element firstname = doc.createElement("FirstName");
firstname.appendChild(doc.createTextNode(FirstName));
contact.appendChild(firstname);
Element lastname = doc.createElement("LastName");
lastname.appendChild(doc.createTextNode(LastName));
contact.appendChild(lastname);
Element PN = doc.createElement("PhoneNumber");
PN.appendChild(doc.createTextNode(java.lang.Long.toString(PhoneNumber)));
contact.appendChild(PN);
}
}
Enter Your FirstName =
xxxxxxxx
Enter Your LastName =
yyyyyyyy
Enter Your PhoneNumber =
7896456123693
void WriteToXMLFile() throws Exception{
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
source = new DOMSource(doc);
result = new StreamResult(new File(filePathString));
transformer.transform(source, result);
System.out.println("Contact Saved !");
}
java.lang.NullPointerException
at xmlphonebook.StoreContactInformation.WriteToXMLFile(StoreContactInformation.java:105)
at xmlphonebook.StoreContactInformation.<init>(StoreContactInformation.java:65)
at xmlphonebook.XMLPhoneBook.storeContactInfo(XMLPhoneBook.java:35)
at xmlphonebook.XMLPhoneBook.main(XMLPhoneBook.java:43)
请告诉我我犯了什么错误 我在我的工作区复制了你所有的类，确实有NPE，但正如我在之前的一篇评论中提到的，
transformer.setOutputProperty（OutputKeys.INDENT，“是”）
transformer
为NULL
，我通过调试和保留断点来检查它，并使用与我的评论中提到的相同的解决方案来修复它
这就是我在你的构造函数中解决它的方法
StoreContactInformation(String fn, String ln, long pn) throws Exception {
filePathString="PhoneBook.xml"; //File Path is the current working directory.
f = new File(filePathString);
FirstName=fn;
LastName=ln;
PhoneNumber=pn;
docFactory = DocumentBuilderFactory.newInstance();
docBuilder = docFactory.newDocumentBuilder();
transformerFactory = TransformerFactory.newInstance();
/******* added this line ******************/
transformer=transformerFactory.newTransformer();
/******* added this line ******************/
// check if the XML file exist already !
if(f.exists() && !f.isDirectory()) {
//if exist
UpdateXMLFile();
WriteToXMLFile();
}else{
//if do not exist
CreateXMLFile();
WriteToXMLFile();
}
}
得到了这个输出
输入您的名字=xxxx
输入您的姓氏=yyyy
输入您的电话号码=123456
联系人已保存
奇怪的名字！您的getter无效，并通过调用setter更新对象！为什么要使用那么多实例字段而不是局部变量？这使得关于对象状态的争论变得非常困难，这可能是您现在无法说出NPE原因的原因。我猜这是您的行号105，transformer.setOutputProperty（OutputKeys.INDENT，“yes”），在构造函数中，我没有看到transformer
变量被初始化。也许这会有帮助，transformer=TransformerFactory.newTransformer（）
@Shrikant我已经厌倦了，而且还是一样的。@isnot2bad抱歉编程不好，我对这个很陌生。那么，您能告诉我们您的线路号是105吗