Android应用程序在开始时停止工作，堆栈跟踪不指向代码中停止工作的位置

Question

我正试图在Android编程中弄清楚开发一个与Facebook集成的真正基本的应用程序。我按照教程制作了一个基本的登录页面，但是应用程序在开始时就崩溃了。我试着自己调试，但几个小时后我没有取得任何成功。真正让我失望的是，错误消息并没有直接告诉我我的代码中的确切位置，我搞砸了，我想我现在缺乏了解他们现在所说的内容。

（https://developers.facebook.com/docs/android/login-with-facebook/v2.2#step1）

以下是错误（我为文本墙道歉）和我的MainActivity / MainFragment类。如果有人能够指出我犯了什么具体的错误（或者我只是接近整个错误），那将是非常棒的。此外，任何有关Android应用程序的一般调试和此类问题的提示也将非常受欢迎。我的思绪仍然没有完全围绕活动生命周期及其方法。

logcat的：

  01-13 05:31:14.216  17714-17730/com.example.harrisonhe.chatstats W/dalvikvm﹕ threadid=12: thread    exiting with uncaught exception (group=0x41e44e30)
  01-13 05:31:14.216  17714-17731/com.example.harrisonhe.chatstats W/dalvikvm﹕ threadid=13: thread      exiting with uncaught exception (group=0x41e44e30)
  01-13 05:31:14.216  17714-17730/com.example.harrisonhe.chatstats E/AndroidRuntime﹕ FATAL EXCEPTION: AsyncTask #1
Process: com.example.harrisonhe.chatstats, PID: 17714
java.lang.RuntimeException: An error occured while executing doInBackground()
        at android.os.AsyncTask$3.done(AsyncTask.java:300)
        at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
        at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
        at java.util.concurrent.FutureTask.run(FutureTask.java:242)
        at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
        at java.lang.Thread.run(Thread.java:864)
 Caused by: java.lang.NullPointerException
        at java.util.concurrent.ConcurrentHashMap.containsKey(ConcurrentHashMap.java:911)
        at com.facebook.internal.Utility.queryAppSettings(Utility.java:673)
        at com.facebook.widget.LoginButton$1.doInBackground(LoginButton.java:678)
        at com.facebook.widget.LoginButton$1.doInBackground(LoginButton.java:675)
        at android.os.AsyncTask$2.call(AsyncTask.java:288)
        at java.util.concurrent.FutureTask.run(FutureTask.java:237)
        at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
        at java.lang.Thread.run(Thread.java:864)
        01-13 05:31:14.226  17714-17731/com.example.harrisonhe.chatstats E/AndroidRuntime_2_crash﹕ crash in the same process: AsyncTask #2
java.lang.RuntimeException: An error occured while executing doInBackground()
        at android.os.AsyncTask$3.done(AsyncTask.java:300)
        at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
        at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
        at java.util.concurrent.FutureTask.run(FutureTask.java:242)
                     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
        java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
        at java.lang.Thread.run(Thread.java:864)
 Caused by: java.lang.NullPointerException
        at java.util.concurrent.ConcurrentHashMap.containsKey(ConcurrentHashMap.java:911)
        at com.facebook.internal.Utility.queryAppSettings(Utility.java:673)
        at com.facebook.widget.LoginButton$1.doInBackground(LoginButton.java:678)
        at com.facebook.widget.LoginButton$1.doInBackground(LoginButton.java:675)
        at android.os.AsyncTask$2.call(AsyncTask.java:288)
        at java.util.concurrent.FutureTask.run(FutureTask.java:237)
        at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
        at java.lang.Thread.run(Thread.java:864)

代码：

public class MainActivity extends FragmentActivity {

private MainFragment mainFragment;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    if(savedInstanceState==null)
    {
        //add fragment on initial activity startup
        mainFragment = new MainFragment();
        getSupportFragmentManager().beginTransaction().add(android.R.id.content, mainFragment).commit();

    }
    else
    {
        // Or set the fragment from restored state info
        mainFragment = (MainFragment) getSupportFragmentManager().findFragmentById(android.R.id.content);
    }

    setContentView(R.layout.activity_main);
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}
}

public class MainFragment extends Fragment{

private static final String TAG = "MainFragment";
// @Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.activity_main, container, false);

    LoginButton authButton = (LoginButton) view.findViewById(R.id.authButton);
    authButton.setFragment(this);
    return view;
}

private Session.StatusCallback callback = new Session.StatusCallback() {
    public void call(Session session, SessionState state, Exception exception) {
        onSessionStateChange(session, state, exception);
    }
};

private void onSessionStateChange(Session session, SessionState state, Exception exception) {
    if (state.isOpened()) {
        Log.i(TAG,"swag420");
        Log.i(TAG, "Logged in...");
    } else if (state.isClosed()) {
        Log.i(TAG, "Logged out...");
    }
}

private UiLifecycleHelper uiHelper;

@Override
public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    uiHelper = new UiLifecycleHelper(getActivity(), callback);
}

@Override
public void onResume(){
    super.onResume();
    /*
     for scenarios where the main activity is launched and user session is
     not null, the session state change notification may not be triggered.
     Trigger it if it's open/closed
    */
    Session session = Session.getActiveSession();
    if(session!=null && (session.isOpened() || session.isClosed()))
    {
        onSessionStateChange(session, session.getState(), null);
    }
    uiHelper.onResume();
   }

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data){
    super.onActivityResult(resultCode, resultCode, data);
    uiHelper.onActivityResult(requestCode,resultCode,data);
}

@Override
public void onPause(){
    super.onPause();
    uiHelper.onDestroy();
}

@Override
public void onSaveInstanceState(Bundle outState){
    super.onSaveInstanceState(outState);
    uiHelper.onSaveInstanceState(outState);
  }
}

Answer 1

至少你知道问题是什么，也许不知道它在哪里。它是一个空指针。查看代码时，我无法确定问题this answer作为参考。在这个答案中，该人没有初始化允许他们连接到互联网的jsonParser。我假设还有其他课程没有显示

这也是我联系到的答案：

  

此外，您无法在UIThread上发出网络请求。这将导致NetworkOnMainThreadException。您将需要使用AsyncTask。检查此NetworkOnMainThreadException

Answer 2

LoginButton需要在元数据中设置您的应用ID（AndroidManifest.xml和strings.xml）。您是否相应地设置了应用ID？ https://developers.facebook.com/docs/android/getting-started