停止播放声音时应用程序停止

Question

我创建了我的 Android 应用，以便在用户 选择选项值 时播放声音，我的代码做得很好。一切正常，但是当我添加我的代码以使用户在他的手机上单击 锁定按钮 时静音或停止声音时效果很好，但是当我 旋转 手机时 horizo​​ntal 发生错误“应用程序意外停止”。我检查了我的代码，并在 onPause 方法中发现了错误。

@Override 
protected void onResume() {

    IntentFilter intentFilter = new IntentFilter();
    intentFilter.addAction(Intent.ACTION_SCREEN_OFF);


    registerReceiver(new IntentListener(), intentFilter);

    super.onResume();
}


@Override
protected void onPause() {
    IntentFilter intentFilter = new IntentFilter();
    super.onPause(); // Don't forget this line
    mp.pause(); // Or whatever the function is to pause it
    unregisterReceiver(new IntentListener());
}
@Override
public void onConfigurationChanged(Configuration newConfig) {
  super.onConfigurationChanged(newConfig);
  setContentView(R.layout.activity);
}

<activity
        android:name="xx"
        android:label="@string/app_name"
        android:configChanges="orientation|keyboardHidden|screenSize">

06-25 13:59:31.442: W/KeyCharacterMap(331): No keyboard for id 0
06-25 13:59:31.442: W/KeyCharacterMap(331): Using default keymap: /system/usr/keychars/qwerty.kcm.bin
06-25 13:59:31.592: D/AndroidRuntime(331): Shutting down VM
06-25 13:59:31.603: W/dalvikvm(331): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
06-25 13:59:31.672: E/AndroidRuntime(331): FATAL EXCEPTION: main
06-25 13:59:31.672: E/AndroidRuntime(331): java.lang.RuntimeException: Unable to pause activity {com.ramadan/com.ramadan.Ramadan}: java.lang.NullPointerException
06-25 13:59:31.672: E/AndroidRuntime(331):  at android.app.ActivityThread.performPauseActivity(ActivityThread.java:3348)
06-25 13:59:31.672: E/AndroidRuntime(331):  at android.app.ActivityThread.performPauseActivity(ActivityThread.java:3305)
06-25 13:59:31.672: E/AndroidRuntime(331):  at android.app.ActivityThread.handlePauseActivity(ActivityThread.java:3288)
06-25 13:59:31.672: E/AndroidRuntime(331):  at android.app.ActivityThread.access$2500(ActivityThread.java:125)
06-25 13:59:31.672: E/AndroidRuntime(331):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2044)
06-25 13:59:31.672: E/AndroidRuntime(331):  at android.os.Handler.dispatchMessage(Handler.java:99)
06-25 13:59:31.672: E/AndroidRuntime(331):  at android.os.Looper.loop(Looper.java:123)
06-25 13:59:31.672: E/AndroidRuntime(331):  at android.app.ActivityThread.main(ActivityThread.java:4627)
06-25 13:59:31.672: E/AndroidRuntime(331):  at java.lang.reflect.Method.invokeNative(Native Method)
06-25 13:59:31.672: E/AndroidRuntime(331):  at java.lang.reflect.Method.invoke(Method.java:521)
06-25 13:59:31.672: E/AndroidRuntime(331):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
06-25 13:59:31.672: E/AndroidRuntime(331):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
06-25 13:59:31.672: E/AndroidRuntime(331):  at dalvik.system.NativeStart.main(Native Method)
06-25 13:59:31.672: E/AndroidRuntime(331): Caused by: java.lang.NullPointerException
06-25 13:59:31.672: E/AndroidRuntime(331):  at     com.ramadan.Ramadan.onPause(Ramadan.java:125)
06-25 13:59:31.672: E/AndroidRuntime(331):  at android.app.Activity.performPause(Activity.java:3842)
06-25 13:59:31.672: E/AndroidRuntime(331):  at android.app.Instrumentation.callActivityOnPause(Instrumentation.java:1190)
06-25 13:59:31.672: E/AndroidRuntime(331):  at android.app.ActivityThread.performPauseActivity(ActivityThread.java:3335)
06-25 13:59:31.672: E/AndroidRuntime(331):  ... 12 more

Answer 1

如果您查看崩溃的 logcat 输出，您将获得更多信息，因为它会告诉您异常的原因。但是，仅仅看上面的代码，你不能用不同的实例调用registerReceiver()和unregisterReceiver()，它们必须是同一个对象。对unregisterReceiver() 的调用可能会提交一个异常，说明接收器实例以前从未注册过。您的代码需要看起来更像这样：

//We need a reference to this instance somehow
private IntentListener listener = new IntentListener();

@Override
public void onResume() {

    IntentFilter intentFilter = new IntentFilter();
    intentFilter.addAction(Intent.ACTION_SCREEN_OFF);

    registerReceiver(listener, intentFilter);

    super.onResume();
}

@Override
public void onPause() {
    super.onPause();
    unregisterReceiver(listener); //must be the same instance you registered!
}

Answer 2

没有 logcat 很难调查问题

但是，您可以通过在清单中添加配置更改来跳过轮换重启

    <activity
        android:name="com.youclassname.xxx"
        android:configChanges="orientation|keyboardHidden|screenSize"/>