Question

我正在开发一个VCard应用程序。这里我已经开始默认联系人活动（地址簿）。

现在，应用程序流程就是这样，

用户启动应用程序。
打开默认联系簿。
用户从列表中选择一个联系人，然后创建所选联系人的Vcard。

现在，当用户在没有选择任何联系人的情况下按下Back Button时，应用程序将被强制关闭。

我已经覆盖BackKeyPress()事件，但它不起作用。该应用程序仍在关闭。

我发布的代码供参考，

    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        Intent intent = new Intent(Intent.ACTION_PICK, ContactsContract.Contacts.CONTENT_URI);
        startActivityForResult(intent, 1);
        Log.d("In Oncreate", "Activity Result");
    }
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
         if (keyCode == KeyEvent.KEYCODE_BACK) {
         //preventing default implementation previous to android.os.Build.VERSION_CODES.ECLAIR
             Toast.makeText(getApplicationContext(), "Back Pressed", 5000).show();
             finish();
         return true;
         }
         return super.onKeyDown(keyCode, event);    
    }
    @Override
    public void onActivityResult(int reqCode, int resultCode, Intent data) {
      super.onActivityResult(reqCode, resultCode, data);

      switch (reqCode) {
        case (1) :
            counter = "Yes";
    Log.d("My Tag", data.getExtras().keySet().toString());
    name_selected = data.getExtras().getString("android.intent.extra.shortcut.NAME");
    Log.d("My Tag", name_selected));
    Intent i = new Intent(getApplicationContext(), BusinessCardActivity.class);
    i.putExtra("name", name_selected);
    i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    getApplicationContext().startActivity(i);
       }
    }
}

Logcat错误： -

12-17 18:41:09.399: E/AndroidRuntime(23456): FATAL EXCEPTION: main
12-17 18:41:09.399: E/AndroidRuntime(23456): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=0, data=null} to activity {com.android.business/com.android.business.ReadContacts}: java.lang.NullPointerException
12-17 18:41:09.399: E/AndroidRuntime(23456):    at android.app.ActivityThread.deliverResults(ActivityThread.java:2536)
12-17 18:41:09.399: E/AndroidRuntime(23456):    at android.app.ActivityThread.handleSendResult(ActivityThread.java:2578)
12-17 18:41:09.399: E/AndroidRuntime(23456):    at android.app.ActivityThread.access$2000(ActivityThread.java:117)
12-17 18:41:09.399: E/AndroidRuntime(23456):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:961)
12-17 18:41:09.399: E/AndroidRuntime(23456):    at android.os.Handler.dispatchMessage(Handler.java:99)
12-17 18:41:09.399: E/AndroidRuntime(23456):    at android.os.Looper.loop(Looper.java:123)
12-17 18:41:09.399: E/AndroidRuntime(23456):    at android.app.ActivityThread.main(ActivityThread.java:3729)
12-17 18:41:09.399: E/AndroidRuntime(23456):    at java.lang.reflect.Method.invokeNative(Native Method)
12-17 18:41:09.399: E/AndroidRuntime(23456):    at java.lang.reflect.Method.invoke(Method.java:507)
12-17 18:41:09.399: E/AndroidRuntime(23456):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:874)
12-17 18:41:09.399: E/AndroidRuntime(23456):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:632)
12-17 18:41:09.399: E/AndroidRuntime(23456):    at dalvik.system.NativeStart.main(Native Method)
12-17 18:41:09.399: E/AndroidRuntime(23456): Caused by: java.lang.NullPointerException
12-17 18:41:09.399: E/AndroidRuntime(23456):    at com.android.business.ReadContacts.onActivityResult(ReadContacts.java:133)
12-17 18:41:09.399: E/AndroidRuntime(23456):    at android.app.Activity.dispatchActivityResult(Activity.java:3908)
12-17 18:41:09.399: E/AndroidRuntime(23456):    at android.app.ActivityThread.deliverResults(ActivityThread.java:2532)

此处用户应该从列表中选择一个联系人，但如果用户在没有选择任何联系人的情况下按下后退按钮，该应用程序将被强制关闭。

Answer 1

使用此...

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

  switch (reqCode) {
    case 1:
    if(data!=null&&resultCode==RESULT_OK){


        counter = "Yes";
Log.d("My Tag", data.getExtras().keySet().toString());
name_selected = data.getExtras().getString("android.intent.extra.shortcut.NAME");
Log.d("My Tag", name_selected));
Intent i = new Intent(getApplicationContext(), BusinessCardActivity.class);
i.putExtra("name", name_selected);
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
getApplicationContext().startActivity(i);
   }
  }
}

Answer 2

在你的OnActivityResult（）中这样做..

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

  switch (reqCode) {
    case (1) :
     if (data != null && resultCode == RESULT_OK) {
        counter = "Yes";
    // Do some operations on the selected contact
     }
   }
}

Answer 3

I have overidden BackKeyPress() event, but its not working. The app is still getting force closed.

因为backKeyPressed()事件会响应Default Contacts activity(Address Book)。不是你的Android应用程序的活动。

当我看到你的代码onActivityResult()和没有任何logcat错误时，我认为这种崩溃可能发生在Default Contacts activity(Address Book)方，而非你的应用方。此外，您必须检查Default Contacts activity(Address Book)是否为Intent处理任何onActivityResult()（结果意图）作为对其他应用程序的响应。

所以 logcat错误会更有帮助。

修改

是的我怀疑，您的数据是NULL

在对Intent进行操作之前，只需检查data是否 null ，

if(data != null) { Log.d("My Tag", data.getExtras().keySet().toString()); name_selected = data.getExtras().getString("android.intent.extra.shortcut.NAME"); Log.d("My Tag", name_selected)); Intent i = new Intent(getApplicationContext(), BusinessCardActivity.class); i.putExtra("name", name_selected); i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK); getApplicationContext().startActivity(i); }

Answer 4

由于onActivityResult方法第133行引发了NullPointerException，您的应用程序将被强制关闭。检查结果是否有效并在那里放一些try catch。

12-17 18:41:09.399: E/AndroidRuntime(23456): Caused by: java.lang.NullPointerException
12-17 18:41:09.399: E/AndroidRuntime(23456):    at com.android.business.ReadContacts.onActivityResult(ReadContacts.java:133)

Answer 5

您是否在管理没有选定联系人的情况？如果用户按下并且未选择任何联系人，则在onActivityResult中，您应该处理“联系人”为空。

应用程序在按下后退键上关闭力量

5 个答案: