新的意图崩溃应用程序

Question

我想点击ListView项目但应用程序崩溃后开始新的活动。如果我注释掉意图初始化，并且只留下吐司消息应用程序不会崩溃。随后问题出现在Intent中。我不知道为什么会发生这种情况。任何帮助将不胜感激。

public class MainActivity extends Activity { 

     private ArrayList<Cinemas> cinema; 
     private CinemasAdapter cinemaAdapter; 
     private ListView list; 

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

      cinema = new Handler().handle(); 
      cinemaAdapter = new CinemasAdapter(this, R.layout.movie_data_row, cinema); 
      list = (ListView) findViewById (R.id.listing1);  
      list.setAdapter(cinemaAdapter); 
      setContentView(list); 

      list.setOnItemClickListener(new OnItemClickListener(){ 
      public void onItemClick (AdapterView<?> parent, View view, int position, long id) 
      { 
       Context context = null; 
       Cinemas movie = cinemaAdapter.getItem(position); 
       Toast.makeText(getBaseContext(), "Click", Toast.LENGTH_LONG).show(); 
       Intent intent = new Intent (context,More.class); 
       startActivity(intent); 
      } 
      }); 
     }  
    } 

这里是logcat的：

03-16 13:33:28.882: E/AndroidRuntime(2536): FATAL EXCEPTION: main 
03-16 13:33:28.882: E/AndroidRuntime(2536): java.lang.NullPointerException 
03-16 13:33:28.882: E/AndroidRuntime(2536):  at android.content.ComponentName.<init>(ComponentName.java:75) 
03-16 13:33:28.882: E/AndroidRuntime(2536):  at android.content.Intent.<init>(Intent.java:3491) 
03-16 13:33:28.882: E/AndroidRuntime(2536):  at com.example.bakumovies.MainActivity$1.onItemClick(MainActivity.java:47) 
03-16 13:33:28.882: E/AndroidRuntime(2536):  at android.widget.AdapterView.performItemClick(AdapterView.java:298) 
03-16 13:33:28.882: E/AndroidRuntime(2536):  at android.widget.AbsListView.performItemClick(AbsListView.java:1100) 
03-16 13:33:28.882: E/AndroidRuntime(2536):  at android.widget.AbsListView$PerformClick.run(AbsListView.java:2749) 
03-16 13:33:28.882: E/AndroidRuntime(2536):  at android.widget.AbsListView$1.run(AbsListView.java:3423) 
03-16 13:33:28.882: E/AndroidRuntime(2536):  at android.os.Handler.handleCallback(Handler.java:725) 
03-16 13:33:28.882: E/AndroidRuntime(2536):  at android.os.Handler.dispatchMessage(Handler.java:92) 
03-16 13:33:28.882: E/AndroidRuntime(2536):  at android.os.Looper.loop(Looper.java:137) 
03-16 13:33:28.882: E/AndroidRuntime(2536):  at android.app.ActivityThread.main(ActivityThread.java:5041) 
03-16 13:33:28.882: E/AndroidRuntime(2536):  at java.lang.reflect.Method.invokeNative(Native Method) 
03-16 13:33:28.882: E/AndroidRuntime(2536):  at java.lang.reflect.Method.invoke(Method.java:511) 
03-16 13:33:28.882: E/AndroidRuntime(2536):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
03-16 13:33:28.882: E/AndroidRuntime(2536):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
03-16 13:33:28.882: E/AndroidRuntime(2536):  at dalvik.system.NativeStart.main(Native Method) 

Answer 1

你已经初始化的背景与空

Context context = null; 

Intent intent = new Intent (context,More.class); 

而且你与上下文开始的意图，这将导致NullPointerException

所以做这样的

Intent intent = new Intent (MainActivity.this, More.class); 

Answer 2

用途：

Intent intent = new Intent (MainActivity.this, More.class); 

而不是

你都拿到一个NullPointerException，因为，你分配给contextnull。