线程的 DefaultUncaughtExceptionHandler 未捕获 AlertDialog onClick() 方法中引发的异常

Question

我在我的Activity 的onCreate() 中为当前线程设置了一个默认的UncaughtExceptionHandler，并从我的AlertDialog 的onClick() 监听器中抛出一个RunTimeException，但没有捕获到异常。我还尝试从onCreateOptionsMenu() 和onOptionsItemSelected() 抛出异常，但没有被捕获。然而，当从onCreate() 或onResume() 抛出时，它会被捕获。

这是我的活动：

public class MainActivity extends AppCompatActivity implements DialogInterface.OnClickListener {

    private static final String TAG = "MainActivity";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Thread.setDefaultUncaughtExceptionHandler(new DefExcHandler());
        Log.d(TAG, "onCreate: "+Thread.currentThread().getName()+" "+Thread.currentThread().getId());

        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setNeutralButton("CRASH", this);
        AlertDialog dialog = builder.create();
        dialog.show();
        dialog.setCancelable(false);
        dialog.setCanceledOnTouchOutside(false);
    }

    @Override
    public void onClick(DialogInterface dialog, int which) {
        dialog.dismiss();
        Log.d(TAG, "onClick: "+Thread.currentThread().getName()+" "+Thread.currentThread().getId());
        throw new RuntimeException();
    }
}

这是我的异常处理程序：

public class DefExcHandler implements Thread.UncaughtExceptionHandler {

    private static final String TAG = "DefExcHandler";

    public DefExcHandler() {
        Log.d(TAG, "DefaultExceptionHandler: ");
    }

    @Override
    public void uncaughtException(Thread thread, Throwable ex) {
        Log.d(TAG, "Uncaught exception caught: "+ex.getMessage()+" "+ex.getCause().toString());
    }
}

根据我在活动中创建的日志消息，线程在onCreate() 和onClick() 中是相同的：

09-27 15:00:57.260 10667-10667/a.b.c D/MainActivity: onCreate: main 1
09-27 15:01:52.680 10667-10667/a.b.c D/MainActivity: onClick: main 1

为什么从onClick()、onCreateOptionsMenu() 或onOptionsItemSelected() 抛出的异常没有被捕获？

Answer 1

我试图重现应用程序的行为。 DefExcHandler 实例似乎被遗漏了，因为它没有记录任何内容，但我尝试了另外两个有效的方法：断点和文件创建。

请尝试在uncaughtException() 内设置断点。我相信它会停止您的代码中的执行。我在下面写了一个示例，它使用文件作为标志来指示未捕获的异常处理程序确实被调用了。

总之，似乎正在调用DefExcHandler.uncaughtException()，但由于某种未知原因（可能是内部竞争条件），Android 无法进行日志记录。

// Example that assures that an UncaughtExceptionHandler
// is being invoked by flagging execution with file creation.

public class MainActivity extends ... implements ... {

    private File mCrashFile;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        mCrashFile = new File(getFilesDir(), "crash");

        // Crash file existence means the application has crashed before.
        Log.d(TAG, "crash file exists: " + mCrashFile.exists());

        // Clear crash flag.
        if (mCrashFile.exists()) {
            Log.d(TAG, "crash file delete: " + mCrashFile.delete());
        }

        Thread.setDefaultUncaughtExceptionHandler(new DefExcHandler());

        ...

    }

    private class DefExcHandler implements Thread.UncaughtExceptionHandler {

        @Override
        public void uncaughtException(Thread thread, Throwable ex) {

            // Set crash flag.
            try {
                mCrashFile.createNewFile();
            } catch (IOException e) {
                // dunno if it really prints anything
                e.printStackTrace();
            }
        }
    }
}