回家后活动崩溃

我有一个edit edit视图的编辑任务活动。当我单击操作栏上的后退按钮时，数据库会更新，并且日志甚至会注册它，但活动在返回时崩溃。主要活动显示在任务活动中添加的文本。下面是home键代码：回家后活动崩溃

public class NewTask extends Activity { 
protected TaskerDbHelper db; 
MyAdapter adapt; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_new_task); 
    db = new TaskerDbHelper(this); 
    setupActionBar(); 
} 

private void setupActionBar() { 

    getActionBar().setDisplayHomeAsUpEnabled(true); 

} 

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

@Override 
public boolean onOptionsItemSelected(MenuItem item) { 
    switch (item.getItemId()) { 
    case android.R.id.home: 
     // This ID represents the Home or Up button. In the case of this 
     // activity, the Up button is shown. Use NavUtils to allow users 
     // to navigate up one level in the application structure. For 
     // more details, see the Navigation pattern on Android Design: 
     // 
     // http://developer.android.com/design/patterns/navigation.html#up-vs-back 
     // 
     EditText t = (EditText) findViewById(R.id.editText1); 
     String s = t.getText().toString(); 
     if (s.equalsIgnoreCase("")) { 
      Toast.makeText(this, "enter the task description first!!", 
        Toast.LENGTH_LONG); 
     } else { 
      Task task = new Task(s, 0); 
      db.addTask(task); 
      Log.d("tasker", "data added"); 
      //t.setText(""); 
      //adapt.add(task); 
      adapt.notifyDataSetChanged(); 
     } 
     setResult(RESULT_OK); 
     finish(); 
     return true; 
    } 
    return super.onOptionsItemSelected(item); 
}

}

的哪些错误？

这里是日志：

08-16 17:56:05.117: E/AndroidRuntime(6162): FATAL EXCEPTION: main 
08-16 17:56:05.117: E/AndroidRuntime(6162): java.lang.NullPointerException 
08-16 17:56:05.117: E/AndroidRuntime(6162):  at com.example.tasker.NewTask.onOptionsItemSelected(NewTask.java:62) 
08-16 17:56:05.117: E/AndroidRuntime(6162):  at android.app.Activity.onMenuItemSelected(Activity.java:2552) 
08-16 17:56:05.117: E/AndroidRuntime(6162):  at com.android.internal.widget.ActionBarView$3.onClick(ActionBarView.java:167) 
08-16 17:56:05.117: E/AndroidRuntime(6162):  at android.view.View.performClick(View.java:4204) 
08-16 17:56:05.117: E/AndroidRuntime(6162):  at android.view.View$PerformClick.run(View.java:17355) 
08-16 17:56:05.117: E/AndroidRuntime(6162):  at android.os.Handler.handleCallback(Handler.java:725) 
08-16 17:56:05.117: E/AndroidRuntime(6162):  at android.os.Handler.dispatchMessage(Handler.java:92) 
08-16 17:56:05.117: E/AndroidRuntime(6162):  at android.os.Looper.loop(Looper.java:137) 
08-16 17:56:05.117: E/AndroidRuntime(6162):  at android.app.ActivityThread.main(ActivityThread.java:5234) 
08-16 17:56:05.117: E/AndroidRuntime(6162):  at java.lang.reflect.Method.invokeNative(Native Method) 
08-16 17:56:05.117: E/AndroidRuntime(6162):  at java.lang.reflect.Method.invoke(Method.java:525) 
08-16 17:56:05.117: E/AndroidRuntime(6162):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:799) 
08-16 17:56:05.117: E/AndroidRuntime(6162):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:566) 
08-16 17:56:05.117: E/AndroidRuntime(6162):  at dalvik.system.NativeStart.main(Native Method)

来源

2013-08-16 Gibran Gul

你在NewTask.java有哪些行62？ –

this：adapt.notifyDataSetChanged（）; –

你如何初始化适应？ – AndroidDev

尝试检查适配器是否空第一

if(adapt != null) { 
    adapt.notifyDataSetChanged(); 
} else { 
    // Initialize and do other stuff with it 
}

而在声明中，声明适应这样

public MyAdapter adapt;

我可以看到您使用的是自定义适配器类。我认为这个问题可能也存在于notifyDataSetChanged()方法中。你可以发布吗？

来源

2013-08-16 13:17:00 AndroidDev

适配器为空，我添加了一个log.v语句来检查它。我正在使用stcok notifyDataSetChanged（）方法。 –

你从来没有真正使它活跃起来。尝试在onCreate（）中加入类似的内容：adapt = new MyAdapter（this，android.R.layout.simple_list_item_1，array）; – AndroidDev

if(adapt != null) { 
    adapt.notifyDataSetChanged(); 
} else { 
    adapt = new Adapter(); 
    listview.setAdapter(adapt); 
}

来源

2013-08-16 13:08:56 TeeTracker

检查从诺亚答案。他是压倒一切的通知（）来访问BaseAdapter

https://stackoverflow.com/a/5327197/2074990

来源

2013-08-16 13:10:34 bofredo

回家后活动崩溃

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