Android getJSON工作，但parseJSON不工作

我试图在代码中使用getJSON和parseJSON，getJSON可以正常工作，但parse不能。我得到一个例外：

java.lang.NullPointerException: Attempt to invoke virtual method 'org.json.JSONObject org.json.JSONArray.getJSONObject(int)' on a null object reference

在主要活动中，我有：

        public void onCellLocationChanged(CellLocation lokacija) {
        super.onCellLocationChanged(lokacija);
        location = (GsmCellLocation) Phone.getCellLocation();
        textCellId.setText(String.valueOf(location.getCid() % 65536));
        textCellLac.setText(String.valueOf(location.getLac()));
        String JSON_URL_string=JSON_URL + "?cellid=" + String.valueOf(location.getCid()%65636);
        getJSON(JSON_URL_string);
        ParseJSON();
    }

getJSON返回如下内容：

{"result":[{"cellname":"BG_ACB1","celllat":"44.81125","celllon":"20.39933","celldir":"0","cellattr":"gsm900"},{"cellname":"SOMB5W1","celllat":"45.783055","celllon":"19.120833","celldir":"100","cellattr":"umts900"}]}

在您看到的getJSON之后，我调用了ParseJSON：

    private void ParseJSON() {
        Intent intent = new Intent(MainActivity.this,ParseJSON.class);
        intent.putExtra(MY_JSON,textCellNameSakriven.getText().toString());
        startActivity(intent);
    }

这里有一个类ParseJSON。如果我在不使用ParseJSON的情况下运行代码，它将正常工作：

public class ParseJSON extends ActionBarActivity {

    private String myJSONString;

    private static final String JSON_ARRAY ="result";
    private static final String CELLNAME = "cellname";

    private JSONArray users = null;

    private int TRACK = 0;

    private TextView textCellName;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Intent intent = getIntent();
        myJSONString = intent.getStringExtra(MainActivity.MY_JSON);

        textCellName=(TextView) findViewById(R.id.textCellName);
        extractJSON();
        showData();
    }

    private void extractJSON(){
        try {
            JSONObject jsonObject = new JSONObject(myJSONString);
            users = jsonObject.getJSONArray(JSON_ARRAY);
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

    private void showData(){
        try {
            JSONObject jsonObject = users.getJSONObject(TRACK);

            textCellName.setText(jsonObject.getString(CELLNAME));

        } catch (JSONException e) {
            e.printStackTrace();
        }
    }
 }

最后，这里是一个日志：

FATAL EXCEPTION: main
 Process: com.zelenigrad.bsavkovic.myapplication, PID: 9862
 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.zelenigrad.bsavkovic.myapplication/com.zelenigrad.bsavkovic.myapplication.ParseJSON}: java.lang.NullPointerException: Attempt to invoke virtual method 'org.json.JSONObject org.json.JSONArray.getJSONObject(int)' on a null object reference
     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2305)
     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2365)
     at android.app.ActivityThread.access$800(ActivityThread.java:148)
     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1283)
     at android.os.Handler.dispatchMessage(Handler.java:102)
     at android.os.Looper.loop(Looper.java:135)
     at android.app.ActivityThread.main(ActivityThread.java:5272)
     at java.lang.reflect.Method.invoke(Native Method)
     at java.lang.reflect.Method.invoke(Method.java:372)
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:909)
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:704)
  Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'org.json.JSONObject org.json.JSONArray.getJSONObject(int)' on a null object reference
     at com.zelenigrad.bsavkovic.myapplication.ParseJSON.showData(ParseJSON.java:59)
     at com.zelenigrad.bsavkovic.myapplication.ParseJSON.onCreate(ParseJSON.java:43)
     at android.app.Activity.performCreate(Activity.java:5977)
     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2258)
     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2365) 
     at android.app.ActivityThread.access$800(ActivityThread.java:148) 
     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1283) 
     at android.os.Handler.dispatchMessage(Handler.java:102) 
     at android.os.Looper.loop(Looper.java:135) 
     at android.app.ActivityThread.main(ActivityThread.java:5272) 
     at java.lang.reflect.Method.invoke(Native Method) 
     at java.lang.reflect.Method.invoke(Method.java:372) 
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:909) 
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:704)

谢谢你的努力

Rgds

您不能使用此选项

JSONObject jsonObject = users.getJSONObject(TRACK);

在您的响应中没有类似的json对象可以为您提供NullPointerException

---

并且对象名称必须始终为

字符串

。您使用的是一个int值跟踪。

我认为您在这里得到了一些异常extractJSON（），通过放置日志或其他内容进行检查是的，您是对的。我从互联网上使用了这个代码，删除了一些我认为不需要的部分。我得看看怎么修。Tnx