Question

您好我在第493行获得了一个nullpointer，标记在下面的代码中。有人可以协助解决这个问题吗？我几乎知道100％是复选框（nieuwbel）。但我无法摆脱异常。

提前谢谢。

@Override     
protected void onPause() { 
    MyBeltegoed dialog = new MyBeltegoed (this, new OnReadyListenerBeltegoed()); 
    nieuwbel = (CheckBox)dialog.findViewById(R.id.nieuwbel); 
    Editor e = mPrefs.edit();   
    e.putBoolean(PREF_BOOL, nieuwbel.isChecked());  <----- Nullpointer             
    e.commit();          
    Toast.makeText(this, "Settings Saved.", Toast.LENGTH_SHORT).show();         
    super.onPause();    
}

Answer 1

尝试获取后，您需要检查nieuwbel是否为null。 findViewById()可能找不到您要找的内容：

返回层次结构中具有给定ID的视图或null

试试这个：

@Override     
protected void onPause() { 
    MyBeltegoed dialog = new MyBeltegoed (this, new OnReadyListenerBeltegoed()); 
    nieuwbel = (CheckBox)dialog.findViewById(R.id.nieuwbel); 
    if (nieuwbel != null) {
        Editor e = mPrefs.edit();   
        e.putBoolean(PREF_BOOL, nieuwbel.isChecked());             
        e.commit();          
        Toast.makeText(this, "Settings Saved.", Toast.LENGTH_SHORT).show();
    } else {
        Toast.makeText(this, "Failed to save settings!", Toast.LENGTH_SHORT).show();
    }
    super.onPause();    
}

Logcat forceclose：

10-31 22:57:36.618: E/AndroidRuntime(1423): FATAL EXCEPTION: main
10-31 22:57:36.618: E/AndroidRuntime(1423): android.app.SuperNotCalledException: Activity {com.sencide/com.sencide.AndroidLogin} did not call through to super.onPause()
10-31 22:57:36.618: E/AndroidRuntime(1423):     at android.app.Activity.performPause(Activity.java:3854)
10-31 22:57:36.618: E/AndroidRuntime(1423):     at android.app.Instrumentation.callActivityOnPause(Instrumentation.java:1191)
10-31 22:57:36.618: E/AndroidRuntime(1423):     at android.app.ActivityThread.performPauseActivity(ActivityThread.java:2341)
10-31 22:57:36.618: E/AndroidRuntime(1423):     at android.app.ActivityThread.performPauseActivity(ActivityThread.java:2311)
10-31 22:57:36.618: E/AndroidRuntime(1423):     at android.app.ActivityThread.handlePauseActivity(ActivityThread.java:2291)
10-31 22:57:36.618: E/AndroidRuntime(1423):     at android.app.ActivityThread.access$1700(ActivityThread.java:117)
10-31 22:57:36.618: E/AndroidRuntime(1423):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:942)
10-31 22:57:36.618: E/AndroidRuntime(1423):     at android.os.Handler.dispatchMessage(Handler.java:99)
10-31 22:57:36.618: E/AndroidRuntime(1423):     at android.os.Looper.loop(Looper.java:123)
10-31 22:57:36.618: E/AndroidRuntime(1423):     at android.app.ActivityThread.main(ActivityThread.java:3683)
10-31 22:57:36.618: E/AndroidRuntime(1423):     at java.lang.reflect.Method.invokeNative(Native Method)
10-31 22:57:36.618: E/AndroidRuntime(1423):     at java.lang.reflect.Method.invoke(Method.java:507)
10-31 22:57:36.618: E/AndroidRuntime(1423):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
10-31 22:57:36.618: E/AndroidRuntime(1423):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
10-31 22:57:36.618: E/AndroidRuntime(1423):     at dalvik.system.NativeStart.main(Native Method)

Answer 2

您是否正确设置了内容视图？确保您使用的是创建的R类，而不是默认的android R类。

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
}

编辑：

您还需要为对话框设置内容视图。

@Override     
protected void onPause() { 
  MyBeltegoed dialog = new MyBeltegoed (this, new OnReadyListenerBeltegoed()); 

  dialog.setContentView(R.layout.custom_dialog); <-- add this

  nieuwbel = (CheckBox)dialog.findViewById(R.id.nieuwbel); 
  Editor e = mPrefs.edit();   
  e.putBoolean(PREF_BOOL, nieuwbel.isChecked());           
  e.commit();          
  Toast.makeText(this, "Settings Saved.", Toast.LENGTH_SHORT).show();         
  super.onPause();    
}

custom_dialog是包含nieuwbel的对话框。（来自http://developer.android.com/guide/topics/ui/dialogs.html#CustomDialog）

Nullpointer与Checkbox.isChecked

2 个答案: