Java：接受字符串或int形式的输入
我正在尝试制作一个简单的偶数或奇数程序。我希望它一直运行，直到用户输入'q'。但是我很难接受“q”作为字符串Java：接受字符串或int形式的输入,java,class,java.util.scanner,Java,Class,Java.util.scanner,我正在尝试制作一个简单的偶数或奇数程序。我希望它一直运行，直到用户输入'q'。但是我很难接受“q”作为字符串 import java.util.Scanner; class EvenOrOdd { public static void main(String[] args) { Scanner myScanner = new Scanner(System.in); System.out.println("Welcome to my program t
import java.util.Scanner;
class EvenOrOdd {
public static void main(String[] args) {
Scanner myScanner = new Scanner(System.in);
System.out.println("Welcome to my program that checks if a number is even or odd.");
while (true) {
System.out.println();
System.out.print("Please type number in a number ['q' to quit]: ");
int number;
String quit;
try {
number = myScanner.nextInt();
} finally {
quit = myScanner.nextLine();
}
if (quit.equals("q")) {
break;
} else if (number % 2 == 0) {
System.out.println(number + " is Even.");
} else {
System.out.println(number + " is Odd.");
}
}
}
}
Exception in thread "main" java.util.InputMismatchException
at java.util.Scanner.throwFor(Unknown Source)
at java.util.Scanner.next(Unknown Source)
at java.util.Scanner.nextInt(Unknown Source)
at java.util.Scanner.nextInt(Unknown Source)
at EvenOrOdd.main(EvenOrOdd.java:19)
我知道这对你们中的许多人来说可能很容易，但我刚刚拿起一本java书，正在努力完成这项任务。任何帮助都将不胜感激 不要使用
myScanner.nextInt（）myScanner.next（）字符串即可。然后，如果它不是“q”，则使用Integer.valueOf（inputString）
获取int
，并检查它是否为偶数/奇数
while (true) {
String input = myScanner.next();
if ("q".equals(input)) {
break;
} else {
int number = Integer.valueOf(input);
if (number % 2 == 0) {
System.out.println(number + " is Even.");
} else {
System.out.println(number + " is Odd.");
}
}
}
不要使用myScanner.nextInt（）
，只需使用myScanner.next（）
获取字符串即可。然后，如果它不是“q”，则使用Integer.valueOf（inputString）
获取int
，并检查它是否为偶数/奇数
while (true) {
String input = myScanner.next();
if ("q".equals(input)) {
break;
} else {
int number = Integer.valueOf(input);
if (number % 2 == 0) {
System.out.println(number + " is Even.");
} else {
System.out.println(number + " is Odd.");
}
}
}
不要使用myScanner.nextInt（）
，只需使用myScanner.next（）
获取字符串即可。然后，如果它不是“q”，则使用Integer.valueOf（inputString）
获取int
，并检查它是否为偶数/奇数
while (true) {
String input = myScanner.next();
if ("q".equals(input)) {
break;
} else {
int number = Integer.valueOf(input);
if (number % 2 == 0) {
System.out.println(number + " is Even.");
} else {
System.out.println(number + " is Odd.");
}
}
}
不要使用myScanner.nextInt（）
，只需使用myScanner.next（）
获取字符串即可。然后，如果它不是“q”，则使用Integer.valueOf（inputString）
获取int
，并检查它是否为偶数/奇数
while (true) {
String input = myScanner.next();
if ("q".equals(input)) {
break;
} else {
int number = Integer.valueOf(input);
if (number % 2 == 0) {
System.out.println(number + " is Even.");
} else {
System.out.println(number + " is Odd.");
}
}
}
从扫描器中取出一个字符串，检查是否为“q”，如果不是，将其转换为int，然后检查偶数或奇数
public static void main(String[] args) {
Scanner myScanner = new Scanner(System.in);
System.out.println("Welcome to my program that checks if a number is even or odd.");
while (true) {
System.out.println();
System.out.print("Please type number in a number ['q' to quit]: ");
String inText = myScanner.next();
if (inText.equals("q")){
break;
}
int number = Integer.valueOf(inText);
if (number % 2 == 0) {
System.out.println(number + " is Even.");
} else {
System.out.println(number + " is Odd.");
}
}
}
从扫描器中取出一个字符串，检查是否为“q”，如果不是，将其转换为int，然后检查偶数或奇数
public static void main(String[] args) {
Scanner myScanner = new Scanner(System.in);
System.out.println("Welcome to my program that checks if a number is even or odd.");
while (true) {
System.out.println();
System.out.print("Please type number in a number ['q' to quit]: ");
String inText = myScanner.next();
if (inText.equals("q")){
break;
}
int number = Integer.valueOf(inText);
if (number % 2 == 0) {
System.out.println(number + " is Even.");
} else {
System.out.println(number + " is Odd.");
}
}
}
从扫描器中取出一个字符串，检查是否为“q”，如果不是，将其转换为int，然后检查偶数或奇数
public static void main(String[] args) {
Scanner myScanner = new Scanner(System.in);
System.out.println("Welcome to my program that checks if a number is even or odd.");
while (true) {
System.out.println();
System.out.print("Please type number in a number ['q' to quit]: ");
String inText = myScanner.next();
if (inText.equals("q")){
break;
}
int number = Integer.valueOf(inText);
if (number % 2 == 0) {
System.out.println(number + " is Even.");
} else {
System.out.println(number + " is Odd.");
}
}
}
从扫描器中取出一个字符串，检查是否为“q”，如果不是，将其转换为int，然后检查偶数或奇数
public static void main(String[] args) {
Scanner myScanner = new Scanner(System.in);
System.out.println("Welcome to my program that checks if a number is even or odd.");
while (true) {
System.out.println();
System.out.print("Please type number in a number ['q' to quit]: ");
String inText = myScanner.next();
if (inText.equals("q")){
break;
}
int number = Integer.valueOf(inText);
if (number % 2 == 0) {
System.out.println(number + " is Even.");
} else {
System.out.println(number + " is Odd.");
}
}
}
你可以这样做，我发现在这种情况下，布尔值比while（true）和break更适合循环：
public class EvenOrOdd {
public static void main(String[] args) {
Scanner myScanner = new Scanner(System.in);
System.out
.println("Welcome to my program that checks if a number is even or odd.");
boolean enterLoop = true;
while (enterLoop) {
System.out.println();
System.out.print("Please type number in a number ['q' to quit]: ");
String scannerinput = myScanner.nextLine();
if (scannerinput.equals("q")) {
enterLoop = false;
} else {
checkNumber(scannerinput);
}
}
}
private static void checkNumber(String scannerinput) {
try {
int number = Integer.parseInt(scannerinput);
if (number % 2 == 0) {
System.out.println(number + " is Even.");
} else {
System.out.println(number + " is Odd.");
}
} catch (Exception e) {
System.out.println("No Number!");
}
}
}你可以这样做，我发现在这种情况下，布尔值比while（true）和break更适合循环：
public class EvenOrOdd {
public static void main(String[] args) {
Scanner myScanner = new Scanner(System.in);
System.out
.println("Welcome to my program that checks if a number is even or odd.");
boolean enterLoop = true;
while (enterLoop) {
System.out.println();
System.out.print("Please type number in a number ['q' to quit]: ");
String scannerinput = myScanner.nextLine();
if (scannerinput.equals("q")) {
enterLoop = false;
} else {
checkNumber(scannerinput);
}
}
}
private static void checkNumber(String scannerinput) {
try {
int number = Integer.parseInt(scannerinput);
if (number % 2 == 0) {
System.out.println(number + " is Even.");
} else {
System.out.println(number + " is Odd.");
}
} catch (Exception e) {
System.out.println("No Number!");
}
}
}你可以这样做，我发现在这种情况下，布尔值比while（true）和break更适合循环：
public class EvenOrOdd {
public static void main(String[] args) {
Scanner myScanner = new Scanner(System.in);
System.out
.println("Welcome to my program that checks if a number is even or odd.");
boolean enterLoop = true;
while (enterLoop) {
System.out.println();
System.out.print("Please type number in a number ['q' to quit]: ");
String scannerinput = myScanner.nextLine();
if (scannerinput.equals("q")) {
enterLoop = false;
} else {
checkNumber(scannerinput);
}
}
}
private static void checkNumber(String scannerinput) {
try {
int number = Integer.parseInt(scannerinput);
if (number % 2 == 0) {
System.out.println(number + " is Even.");
} else {
System.out.println(number + " is Odd.");
}
} catch (Exception e) {
System.out.println("No Number!");
}
}
}你可以这样做，我发现在这种情况下，布尔值比while（true）和break更适合循环：
public class EvenOrOdd {
public static void main(String[] args) {
Scanner myScanner = new Scanner(System.in);
System.out
.println("Welcome to my program that checks if a number is even or odd.");
boolean enterLoop = true;
while (enterLoop) {
System.out.println();
System.out.print("Please type number in a number ['q' to quit]: ");
String scannerinput = myScanner.nextLine();
if (scannerinput.equals("q")) {
enterLoop = false;
} else {
checkNumber(scannerinput);
}
}
}
private static void checkNumber(String scannerinput) {
try {
int number = Integer.parseInt(scannerinput);
if (number % 2 == 0) {
System.out.println(number + " is Even.");
} else {
System.out.println(number + " is Odd.");
}
} catch (Exception e) {
System.out.println("No Number!");
}
}
}这是因为程序需要int类型的输入，基本上程序输出：请在数字中键入数字['q'以退出]，然后它将到达myScanner.nextInt（）行并将等待输入，由于“q”不是整数，它将引发异常
一个快速的解决方案是使用myScanner.nextLine（）
，然后将字符串转换为整数，除非它等于“q”。大概是这样的：
import java.util.Scanner;
public class EvenOrOdd {
public static void main(String[] args) {
Scanner myScanner = new Scanner(System.in);
System.out.println("Welcome to my program that checks if a number is even or odd.");
while (true) {
System.out.println();
System.out.print("Please type number in a number ['q' to quit]: ");
String string = myScanner.nextLine();
int number = 0;
if (string.equals("q")) {
myScanner.close(); // Close the scanner.
break;
} else if ((number = toInteger(string)) == -1){ // Is the string a number, less than Integer.MAX_VALUE and greater than Integer.MIN_VALUE?
System.out.printf("%s is not a valid integer!%n",string);
} else if (number % 2 == 0) {
System.out.println(number + " is Even.");
} else {
System.out.println(number + " is Odd.");
}
}
}
private static int toInteger(String str){
try{
return Math.abs(Integer.parseInt(str));
}catch(NumberFormatException e){
return -1;
}
}
}
顺便说一下，请始终关闭扫描仪，否则可能会发生资源泄漏。这是因为程序需要int类型的输入，基本上是程序输出：请在数字中键入数字['q'退出]，然后它将到达myScanner.nextInt（）行并将等待输入，由于“q”不是整数，它将引发异常
import java.util.Scanner;
class EvenOrOdd {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println("Welcome to my program that checks if a number is even or odd.");
while (true) {
System.out.print("\nPlease type number in a number ['q' to quit]: ");
String input = scanner.next();
if (input.equals("q")) {
break;
} else {
int number = Integer.parseInt(input);
System.out.print(number + " is ");
System.out.print(number%2 == 0 ? "Even." : "Odd.");
}
}
}
}
一个快速的解决方案是使用myScanner.nextLine（）
，然后将字符串转换为整数，除非它等于“q”。大概是这样的：
import java.util.Scanner;
public class EvenOrOdd {
public static void main(String[] args) {
Scanner myScanner = new Scanner(System.in);
System.out.println("Welcome to my program that checks if a number is even or odd.");
while (true) {
System.out.println();
System.out.print("Please type number in a number ['q' to quit]: ");
String string = myScanner.nextLine();
int number = 0;
if (string.equals("q")) {
myScanner.close(); // Close the scanner.
break;
} else if ((number = toInteger(string)) == -1){ // Is the string a number, less than Integer.MAX_VALUE and greater than Integer.MIN_VALUE?
System.out.printf("%s is not a valid integer!%n",string);
} else if (number % 2 == 0) {
System.out.println(number + " is Even.");
} else {
System.out.println(number + " is Odd.");
}
}
}
private static int toInteger(String str){
try{
return Math.abs(Integer.parseInt(str));
}catch(NumberFormatException e){
return -1;
}
}
}
顺便说一下，请始终关闭扫描仪，否则可能会发生资源泄漏。这是因为程序需要int类型的输入，基本上是程序输出：请在数字中键入数字['q'退出]，然后它将到达myScanner.nextInt（）行并将等待输入，由于“q”不是整数，它将引发异常
import java.util.Scanner;
class EvenOrOdd {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println("Welcome to my program that checks if a number is even or odd.");
while (true) {
System.out.print("\nPlease type number in a number ['q' to quit]: ");
String input = scanner.next();
if (input.equals("q")) {
break;
} else {
int number = Integer.parseInt(input);
System.out.print(number + " is ");
System.out.print(number%2 == 0 ? "Even." : "Odd.");
}
}
}
}
一个快速的解决方案是使用myScanner.nextLine（）
，然后将字符串转换为整数，除非它等于“q”。大概是这样的：
import java.util.Scanner;
public class EvenOrOdd {
public static void main(String[] args) {
Scanner myScanner = new Scanner(System.in);
System.out.println("Welcome to my program that checks if a number is even or odd.");
while (true) {
System.out.println();
System.out.print("Please type number in a number ['q' to quit]: ");
String string = myScanner.nextLine();
int number = 0;
if (string.equals("q")) {
myScanner.close(); // Close the scanner.
break;
} else if ((number = toInteger(string)) == -1){ // Is the string a number, less than Integer.MAX_VALUE and greater than Integer.MIN_VALUE?
System.out.printf("%s is not a valid integer!%n",string);
} else if (number % 2 == 0) {
System.out.println(number + " is Even.");
} else {
System.out.println(number + " is Odd.");
}
}
}
private static int toInteger(String str){
try{
return Math.abs(Integer.parseInt(str));
}catch(NumberFormatException e){
return -1;
}
}
}
顺便说一下，请始终关闭扫描仪，否则可能会发生资源泄漏。这是因为程序需要int类型的输入，基本上是程序输出：请在数字中键入数字['q'退出]，然后它将到达myScanner.nextInt（）行并将等待输入，由于“q”不是整数，它将引发异常
import java.util.Scanner;
class EvenOrOdd {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println("Welcome to my program that checks if a number is even or odd.");
while (true) {
System.out.print("\nPlease type number in a number ['q' to quit]: ");
String input = scanner.next();
if (input.equals("q")) {
break;
} else {
int number = Integer.parseInt(input);
System.out.print(number + " is ");
System.out.print(number%2 == 0 ? "Even." : "Odd.");
}
}
}
}
一个快速的解决方案是使用myScanner.nextLine（）
，然后将字符串转换为整数，除非它等于“q”。大概是这样的：
import java.util.Scanner;
public class EvenOrOdd {
public static void main(String[] args) {
Scanner myScanner = new Scanner(System.in);
System.out.println("Welcome to my program that checks if a number is even or odd.");
while (true) {
System.out.println();
System.out.print("Please type number in a number ['q' to quit]: ");
String string = myScanner.nextLine();
int number = 0;
if (string.equals("q")) {
myScanner.close(); // Close the scanner.
break;
} else if ((number = toInteger(string)) == -1){ // Is the string a number, less than Integer.MAX_VALUE and greater than Integer.MIN_VALUE?
System.out.printf("%s is not a valid integer!%n",string);
} else if (number % 2 == 0) {
System.out.println(number + " is Even.");
} else {
System.out.println(number + " is Odd.");
}
}
}
private static int toInteger(String str){
try{
return Math.abs(Integer.parseInt(str));
}catch(NumberFormatException e){
return -1;
}
}
}
顺便说一下，请始终关闭扫描仪，否则可能会发生资源泄漏
import java.util.Scanner;
class EvenOrOdd {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println("Welcome to my program that checks if a number is even or odd.");
while (true) {
System.out.print("\nPlease type number in a number ['q' to quit]: ");
String input = scanner.next();
if (input.equals("q")) {
break;
} else {
int number = Integer.parseInt(input);
System.out.print(number + " is ");
System.out.print(number%2 == 0 ? "Even." : "Odd.");
}
}
}
}
那就行了。：）
那就行了。：）
那就行了。：）
那就行了。：） 试试这种方法。查看代码注释以了解更多详细信息
import java.util.Scanner;
class EvenOrOdd {
public static void main(String[] args) {
Scanner myScanner = new Scanner(System.in);
System.out.println("Welcome to my program that checks if a number is even or odd.");
String input=null;
int number;
boolean flag=true; // loop flag
do {
System.out.println();
System.out.print("Please type number in a number ['q' to quit]: ");
// Take user input as String
input=myScanner.nextLine();
try
{
// convert the string value to integer value
number = Integer.parseInt(input);
if (number % 2 == 0)
{
System.out.println(number + " is Even.");
}
else
{
System.out.println(number + " is Odd.");
}
}
catch (NumberFormatException nfe)
{
// control goes here if input is not integer value
if(input.equals("q")) // exist option
flag=false;
else // invalid input
System.out.println("Invalid input, Please enter integer value or (q) to exist");
}
} while (flag);
}
}
试试这种方法。查看代码注释以了解更多详细信息
import java.util.Scanner;
class EvenOrOdd {
public static void main(String[] args) {
Scanner myScanner = new Scanner(System.in);
System.out.println("Welcome to my program that checks if a number is even or odd.");
String input=null;
int number;
boolean flag=true; // loop flag
do {
System.out.println();
System.out.print("Please type number in a number ['q' to quit]: ");
// Take user input as String
input=myScanner.nextLine();
try
{
// convert the string value to integer value
number = Integer.parseInt(input);
if (number % 2 == 0)
{
System.out.println(number + " is Even.");
}
else
{
System.out.println(number + " is Odd.");
}
}
catch (NumberFormatException nfe)
{
// control goes here if input is not integer value
if(input.equals("q")) // exist option
flag=false;
else // invalid input
System.out.println("Invalid input, Please enter integer value or (q) to exist");
}
} while (flag);
}
}
试试这种方法。查看代码注释以了解更多详细信息
import java.util.Scanner;
class EvenOrOdd {
public static void main(String[] args) {
Scanner myScanner = new Scanner(System.in);
System.out.println("Welcome to my program that checks if a number is even or odd.");
String input=null;
int number;
boolean flag=true; // loop flag
do {
System.out.println();
System.out.print("Please type number in a number ['q' to quit]: ");
// Take user input as String
input=myScanner.nextLine();
try
{
// convert the string value to integer value
number = Integer.parseInt(input);
if (number % 2 == 0)
{
System.out.println(number + " is Even.");
}
else
{
System.out.println(number + " is Odd.");
}
}
catch (NumberFormatException nfe)
{
// control goes here if input is not integer value
if(input.equals("q")) // exist option
flag=false;
else // invalid input
System.out.println("Invalid input, Please enter integer value or (q) to exist");
}
} while (flag);
}
}
试试这种方法。查看代码注释以了解更多详细信息
import java.util.Scanner;
class EvenOrOdd {
public static void main(String[] args) {
Scanner myScanner = new Scanner(System.in);
System.out.println("Welcome to my program that checks if a number is even or odd.");
String input=null;
int number;
boolean flag=true; // loop flag
do {
System.out.println();
System.out.print("Please type number in a number ['q' to quit]: ");
// Take user input as String
input=myScanner.nextLine();
try
{
// convert the string value to integer value
number = Integer.parseInt(input);
if (number % 2 == 0)
{
System.out.println(number + " is Even.");
}
else
{
System.out.println(number + " is Odd.");
}
}
catch (NumberFormatException nfe)
{
// control goes here if input is not integer value
if(input.equals("q")) // exist option
flag=false;
else // invalid input
System.out.println("Invalid input, Please enter integer value or (q) to exist");
}
} while (flag);
}
}
您应该更新您的方法流，实际上您正在尝试通过字符串的and intger验证，因此首先将输入作为string
并检查它是否是退出字符q，如果不是，则尝试使用Integer.parseInt（输入）将字符串解析为andint
原语
并测试它是奇数还是偶数。
如果进程失败，假设它既不是一个q也不是一个数字（任何其他字符），则会提示用户使用一个有效数字或“q”退出：
您应该更新您的方法流，实际上您正在尝试通过字符串的and intger验证，因此首先将输入作为string
并检查它是否是退出字符q，如果不是，则尝试使用Integer.parseInt（输入）将字符串解析为andint
原语
并测试它是奇数还是偶数。
如果进程失败，则假定它为nei