应用程序获取强制关闭后退键按下

Question

我正在使用VCard应用程序。在这里我开始了默认联系人活动（地址簿）。现在

，应用程序的流程是这样的，

• 用户启动应用程序。
• 默认联系簿已打开。
• 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，当用户按下Back Button而没有选择任何联系人时，应用程序会强制关闭。

我有事件BackKeyPress()事件，但它不工作。该应用程序仍在关闭。

我张贴的参考代码，

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的错误： -

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) 

这里，用户应该从列表中选择一个联系人，但如果用户按下后退按钮没有选择任何联系人，该应用程序就会关闭。

Answer 1

在你OnActivityResult（）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 2

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

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

当我看到你的onActivityResult()和代码，而无需任何的logcat错误我想这可能坠毁在Default Contacts activity(Address Book)方不要在你的应用程序一侧发生。您也必须检查是否为Default Contacts activity(Address Book)作为对其他应用程序的响应目的处理任何Intent（受邀意向）onActivityResult()。

所以logcat错误将在这里更有帮助。

编辑：

是啊，因为我有一个疑问，你造成数据是NULL

上Intent做术前只检查data是否空与否，

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 3

您是否管理没有选定联系人的情况？如果用户按下并且没有选择联系人，请在onActivityResult中处理“联系人”为空。

Answer 4

你的应用程序获取强制关闭因您的onActivityResult方法，管线133抛出一个NullPointerException。检查结果是否有效，并在那里放一些尝试。

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

使用本...

 @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); 
    } 
    } 
}