Java JSONObject创建引发空指针异常
我在安卓工作室,我正试图创建一个安卓应用程序,可以做一些网络。我可以获取一些JSON数据,但每当我将获取的字符串转换为Java JSONObject创建引发空指针异常,java,android,json,nullpointerexception,Java,Android,Json,Nullpointerexception,我在安卓工作室,我正试图创建一个安卓应用程序,可以做一些网络。我可以获取一些JSON数据,但每当我将获取的字符串转换为JSONObject,就会抛出NullPointerException。以下是我的日志错误: Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference at org.j
JSONObject
,就会抛出NullPointerException
。以下是我的日志错误:
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference
at org.json.JSONTokener.nextCleanInternal(JSONTokener.java:116)
at org.json.JSONTokener.nextValue(JSONTokener.java:94)
at org.json.JSONObject.<init>(JSONObject.java:156)
at org.json.JSONObject.<init>(JSONObject.java:173)
at com.daita.getdusa.GetDataTask.doInBackground(GetDataTask.java:58)
at com.daita.getdusa.GetDataTask.doInBackground(GetDataTask.java:21)
at android.os.AsyncTask$2.call(AsyncTask.java:295)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:234)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)
编辑
我被要求放更多的源代码,所以它在这里(异步任务)
公共类GetDataTask扩展了AsyncTask{
文本视图提交视图;
公共GetDataTask(TextView submitView){
this.submitView=submitView;
}
@凌驾
受保护的void onPreExecute(){
super.onPreExecute();
submitView.setText(“加载…”);
}
@凌驾
受保护的void onPostExecute(字符串s){
super.onPostExecute(s);
submitView.setText(s);
}
@凌驾
受保护的字符串背景(无效…无效){
字符串结果;
结果=getJSON(“http://api.datausa.io/attrs/geo/");
JSONArray数据;
List parsedData=null;
列表大地水准面=新ArrayList();
试一试{
JSONObject JSONObject=新JSONObject(结果);
data=jsonObject.getJSONArray(“数据”);
parsedData=newarraylist();
Log.i(“DUSA”,String.valueOf(jsonObject.length());
对于(int i=0;i
注意:如果您需要实时源代码更新,请查看这些文件,尝试为您完成所有更新,但让我一步一步地为您简化:
package com.daita.getdusa;
import android.content.Context;
import android.os.AsyncTask;
import android.widget.TextView;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
/**
* Created by User on 8/12/2016.
*/
public class GetDataTask extends AsyncTask<String, Void, Void>{
// Put in Main never here.
String result;
String allValues;
Context context;
public GetDataTask(Context mContext){
this.context = mContext;
}
@Override
protected void onPreExecute() {
super.onPreExecute();
((TextView)((MainActivity)context).findViewById(R.id.resultView)).setText("Loading...");
}
@Override
protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
((TextView)((MainActivity)context).findViewById(R.id.resultView)).setText(result);
}
@Override
protected Void doInBackground(String... strings) {
HttpURLConnection c = null;
try {
URL u = new URL("http://api.datausa.io/attrs/geo/"); // use urls first value
c = (HttpURLConnection) u.openConnection();
int status = c.getResponseCode();
switch (status) {
case 200:
case 201:
BufferedReader br = new BufferedReader(new InputStreamReader(c.getInputStream()));
StringBuilder sb = new StringBuilder();
String line;
while ((line = br.readLine()) != null) {
sb.append(line + "\n");
}
br.close();
result = sb.toString();
getValue();
}
} catch (Exception ex) {
ex.printStackTrace();
} finally {
if (c != null) {
try {
c.disconnect();
} catch (Exception ex) {
}
}
}
return null;
}
public void getValue() {
// FIX IT
// Parse the JSON properly
}
}
package com.daita.getdusa;
导入android.content.Context;
导入android.os.AsyncTask;
导入android.widget.TextView;
导入java.io.BufferedReader;
导入java.io.InputStreamReader;
导入java.net.HttpURLConnection;
导入java.net.URL;
/**
*用户于2016年8月12日创建。
*/
公共类GetDataTask扩展了AsyncTask{
//在这里放一个总开关。
字符串结果;
字符串所有值;
语境;
公共GetDataTask(上下文mContext){
this.context=mContext;
}
@凌驾
受保护的void onPreExecute(){
super.onPreExecute();
((TextView)((MainActivity)context.findviewbyd(R.id.resultView)).setText(“加载…”);
}
@凌驾
受保护的void onPostExecute(void避免){
super.onPostExecute(避免);
((TextView)((MainActivity)context.findViewById(R.id.resultView)).setText(结果);
}
@凌驾
受保护的Void doInBackground(字符串…字符串){
HttpURLConnection=null;
试一试{
URL u=新的URL(“http://api.datausa.io/attrs/geo/“”;//使用URL作为第一个值
c=(HttpURLConnection)u.openConnection();
int status=c.getResponseCode();
开关(状态){
案例200:
案例201:
BufferedReader br=新的BufferedReader(新的InputStreamReader(c.getInputStream());
StringBuilder sb=新的StringBuilder();
弦线;
而((line=br.readLine())!=null){
sb.追加(第+行“\n”);
}
br.close();
结果=sb.toString();
getValue();
}
}捕获(例外情况除外){
例如printStackTrace();
}最后{
如果(c!=null){
试一试{
c、 断开连接();
}捕获(例外情况除外){
}
}
}
返回null;
}
public void getValue(){
//修好它
//正确解析JSON
}
}
现在了解json解析,数据量很大,您需要以较小的格式响应这个巨大的json,甚至会使在线json格式化程序崩溃。:)
此代码用于显示所有json。希望这有帮助。公共类测试{
public class Test {
static String Json="{'root':{['ratedetails':{['levelOne':{["+ "{'FGROUP':'A','rentalpackage':'2D','NOOFDAYS':'2', 'HOURS':'0', 'PERIODPRICE':'100.00',"+ "'CUSTOMERPERDAY':'50.00', 'DRIVERPERDAY':'50.00' ,'KMALLOWANCE':'2', 'EXTKMALLOWPDAY':'60',"+ "'DRIVERKMCHARGE':'5', 'CUSTOMERKMCHARGE':'3', 'MAXIMUMKMCHARGE':'99999999', 'MAXKMCHRGTYPE':'0'"+",'HIDDEN':'2'},"+ "{'FGROUP':'A','rentalpackage':'2D','NOOFDAYS':'2', 'HOURS':'0', 'PERIODPRICE':'100.00',"+ "'CUSTOMERPERDAY':'50.00', 'DRIVERPERDAY':'50.00','KMALLOWANCE':'2', 'EXTKMALLOWPDAY':'60',"+ "'DRIVERKMCHARGE':'5', 'CUSTOMERKMCHARGE':'3', 'MAXIMUMKMCHARGE':'99999999', 'MAXKMCHRGTYPE':'0'"+",'HIDDEN':'2'}"+ "]}"+ "]}"+ "]}}";
public static void main(String[] args) {
//new Test().main();
String s[]=Json.split(",");
for(int i=0;i<s.length;i++)
{
if(true){
System.out.println(s[i].split(":")[s[i].split(":").length-2].substring(s[i].split(":")[s[i].split(":").length-2].indexOf("'")+1, s[i].split(":")[s[i].split(":").length-2].lastIndexOf("'"))+" "+ s[i].split(":")[s[i].split(":").length-1].substring(s[i].split(":")[s[i].split(":").length-1].indexOf("'")+1, s[i].split(":")[s[i].split(":").length-1].lastIndexOf("'")));
}
else{
System.out.println(s[i].split(":")[0].replace("'", "").trim()+" "+s[i].split(":")[1].replace("'", "").trim()); } } // System.out.println(Json.split(",")[5].split(":")[1].replace("'", "")); } }
静态字符串Json=“{root':{['ratedetails':{['levelOne':{[”+“{'FGROUP':'A','rentalpackage':'2D','NOOFDAYS':'2','HOURS':'0','PERIODPRICE':'100.00',“+“'CUSTOMERPERDAY':'50.00','DRIVERPERDAY':'50.00','KMALLOWANCE':'2','ExtKmallowPay':'60',“+“,'DRIVERKMCHARGE':'5','CUSTOMERKMCHARGE':'3','Maximum 99KmCharge:'Km99KmChr0'”+“,'HIDDEN':'2'},”+“{'FGROUP':'A','rentalpackage':'
package com.daita.getdusa;
import android.content.Context;
import android.os.AsyncTask;
import android.widget.TextView;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
/**
* Created by User on 8/12/2016.
*/
public class GetDataTask extends AsyncTask<String, Void, Void>{
// Put in Main never here.
String result;
String allValues;
Context context;
public GetDataTask(Context mContext){
this.context = mContext;
}
@Override
protected void onPreExecute() {
super.onPreExecute();
((TextView)((MainActivity)context).findViewById(R.id.resultView)).setText("Loading...");
}
@Override
protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
((TextView)((MainActivity)context).findViewById(R.id.resultView)).setText(result);
}
@Override
protected Void doInBackground(String... strings) {
HttpURLConnection c = null;
try {
URL u = new URL("http://api.datausa.io/attrs/geo/"); // use urls first value
c = (HttpURLConnection) u.openConnection();
int status = c.getResponseCode();
switch (status) {
case 200:
case 201:
BufferedReader br = new BufferedReader(new InputStreamReader(c.getInputStream()));
StringBuilder sb = new StringBuilder();
String line;
while ((line = br.readLine()) != null) {
sb.append(line + "\n");
}
br.close();
result = sb.toString();
getValue();
}
} catch (Exception ex) {
ex.printStackTrace();
} finally {
if (c != null) {
try {
c.disconnect();
} catch (Exception ex) {
}
}
}
return null;
}
public void getValue() {
// FIX IT
// Parse the JSON properly
}
}
public class Test {
static String Json="{'root':{['ratedetails':{['levelOne':{["+ "{'FGROUP':'A','rentalpackage':'2D','NOOFDAYS':'2', 'HOURS':'0', 'PERIODPRICE':'100.00',"+ "'CUSTOMERPERDAY':'50.00', 'DRIVERPERDAY':'50.00' ,'KMALLOWANCE':'2', 'EXTKMALLOWPDAY':'60',"+ "'DRIVERKMCHARGE':'5', 'CUSTOMERKMCHARGE':'3', 'MAXIMUMKMCHARGE':'99999999', 'MAXKMCHRGTYPE':'0'"+",'HIDDEN':'2'},"+ "{'FGROUP':'A','rentalpackage':'2D','NOOFDAYS':'2', 'HOURS':'0', 'PERIODPRICE':'100.00',"+ "'CUSTOMERPERDAY':'50.00', 'DRIVERPERDAY':'50.00','KMALLOWANCE':'2', 'EXTKMALLOWPDAY':'60',"+ "'DRIVERKMCHARGE':'5', 'CUSTOMERKMCHARGE':'3', 'MAXIMUMKMCHARGE':'99999999', 'MAXKMCHRGTYPE':'0'"+",'HIDDEN':'2'}"+ "]}"+ "]}"+ "]}}";
public static void main(String[] args) {
//new Test().main();
String s[]=Json.split(",");
for(int i=0;i<s.length;i++)
{
if(true){
System.out.println(s[i].split(":")[s[i].split(":").length-2].substring(s[i].split(":")[s[i].split(":").length-2].indexOf("'")+1, s[i].split(":")[s[i].split(":").length-2].lastIndexOf("'"))+" "+ s[i].split(":")[s[i].split(":").length-1].substring(s[i].split(":")[s[i].split(":").length-1].indexOf("'")+1, s[i].split(":")[s[i].split(":").length-1].lastIndexOf("'")));
}
else{
System.out.println(s[i].split(":")[0].replace("'", "").trim()+" "+s[i].split(":")[1].replace("'", "").trim()); } } // System.out.println(Json.split(",")[5].split(":")[1].replace("'", "")); } }