旋转屏幕后尝试从活动中接收响应时，Android应用程序崩溃

Question

I'm writing an application that has a main activity that on creation sends the intent to use the standard camera app. The camera app takes a picture and returns the result to the main activity, which then decides on the action to perform. If the screen is rotated while the camera app is on, it fails to return a response to the main activity, otherwise it works flawlessly. Here follows the code structure

public class MainActivity extends Activity {

    private static final int CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE = 100;
    public static final int MEDIA_TYPE_IMAGE = 1;
    private Uri fileUri;

    /** Create a file Uri for saving an image or video */
    private static Uri getOutputMediaFileUri(int type){
          return Uri.fromFile(getOutputMediaFile(type));
    }

    /** Create a File for saving an image or video */
    private static File getOutputMediaFile(int type){
        // To be safe, you should check that the SDCard is mounted
        // using Environment.getExternalStorageState() before doing this.

        File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
                  Environment.DIRECTORY_PICTURES), "MyApp");
        // This location works best if you want the created images to be shared
        // between applications and persist after your app has been uninstalled.

        // Create the storage directory if it does not exist
        if (! mediaStorageDir.exists()){
            if (! mediaStorageDir.mkdirs()){
                Log.d("MyApp", "failed to create directory");
                return null;
            }
        }

        // Create a media file name
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
        File mediaFile;
        if (type == MEDIA_TYPE_IMAGE){
            mediaFile = new File(mediaStorageDir.getPath() + File.separator +
            "IMG_"+ timeStamp + ".jpg");
        } else if(type == MEDIA_TYPE_VIDEO) {
            mediaFile = new File(mediaStorageDir.getPath() + File.separator +
            "VID_"+ timeStamp + ".mp4");
        } else {
            return null;
        }

        return mediaFile;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // create Intent to take a picture and return control to the calling application
        Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

        fileUri = getOutputMediaFileUri(MEDIA_TYPE_IMAGE); // create a file to save the image
        intent.putExtra(MediaStore.EXTRA_OUTPUT, fileUri); // set the image file name

        // start the image capture Intent
        startActivityForResult(intent, CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if (requestCode == CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE) {
            if (resultCode == RESULT_OK) {
                // Image captured and saved to fileUri specified in the Intent

                <do stuff>

                // Open the image
                Intent intent = new Intent();
                intent.setAction(Intent.ACTION_VIEW);
                intent.setDataAndType(fileUri, "image/*");
                startActivity(intent);
            }
        }
    }
}

Here's the log

07-14 19:11:10.768: E/BitmapFactory(22377): Unable to decode stream: java.io.FileNotFoundException: /storage/emulated/0/Pictures/MyApp/IMG_20140714_191110.jpg: open failed: ENOENT (No such file or directory)
07-14 19:11:10.778: E/AndroidRuntime(22377): FATAL EXCEPTION: main
07-14 19:11:10.778: E/AndroidRuntime(22377): Process: com.domain.myapp, PID: 22377
07-14 19:11:10.778: E/AndroidRuntime(22377): java.lang.RuntimeException: Unable to resume activity {com.domain.myapp/com.domain.myapp.MainActivity}: java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=100, result=-1, data=null} to activity {com.domain.myapp/com.domain.myapp.MainActivity}: java.lang.NullPointerException
07-14 19:11:10.778: E/AndroidRuntime(22377):    at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2774)
07-14 19:11:10.778: E/AndroidRuntime(22377):    at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2803)
07-14 19:11:10.778: E/AndroidRuntime(22377):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2238)
07-14 19:11:10.778: E/AndroidRuntime(22377):    at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3724)
07-14 19:11:10.778: E/AndroidRuntime(22377):    at android.app.ActivityThread.access$900(ActivityThread.java:135)
07-14 19:11:10.778: E/AndroidRuntime(22377):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1202)
07-14 19:11:10.778: E/AndroidRuntime(22377):    at android.os.Handler.dispatchMessage(Handler.java:102)
07-14 19:11:10.778: E/AndroidRuntime(22377):    at android.os.Looper.loop(Looper.java:136)
07-14 19:11:10.778: E/AndroidRuntime(22377):    at android.app.ActivityThread.main(ActivityThread.java:5001)
07-14 19:11:10.778: E/AndroidRuntime(22377):    at java.lang.reflect.Method.invokeNative(Native Method)
07-14 19:11:10.778: E/AndroidRuntime(22377):    at java.lang.reflect.Method.invoke(Method.java:515)
07-14 19:11:10.778: E/AndroidRuntime(22377):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
07-14 19:11:10.778: E/AndroidRuntime(22377):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
07-14 19:11:10.778: E/AndroidRuntime(22377):    at dalvik.system.NativeStart.main(Native Method)
07-14 19:11:10.778: E/AndroidRuntime(22377): Caused by: java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=100, result=-1, data=null} to activity {com.domain.myapp/com.domain.myapp.MainActivity}: java.lang.NullPointerException
07-14 19:11:10.778: E/AndroidRuntime(22377):    at android.app.ActivityThread.deliverResults(ActivityThread.java:3351)
07-14 19:11:10.778: E/AndroidRuntime(22377):    at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2761)
07-14 19:11:10.778: E/AndroidRuntime(22377):    ... 13 more
07-14 19:11:10.778: E/AndroidRuntime(22377): Caused by: java.lang.NullPointerException
07-14 19:11:10.778: E/AndroidRuntime(22377):    at com.domain.myapp.MainActivity.draw_interface(MainActivity.java:97)
07-14 19:11:10.778: E/AndroidRuntime(22377):    at com.domain.myapp.MainActivity.draw(MainActivity.java:188)
07-14 19:11:10.778: E/AndroidRuntime(22377):    at com.domain.myapp.MainActivity.onActivityResult(MainActivity.java:234)
07-14 19:11:10.778: E/AndroidRuntime(22377):    at android.app.Activity.dispatchActivityResult(Activity.java:5423)
07-14 19:11:10.778: E/AndroidRuntime(22377):    at android.app.ActivityThread.deliverResults(ActivityThread.java:3347)
07-14 19:11:10.778: E/AndroidRuntime(22377):    ... 14 more
07-14 19:13:08.278: E/BitmapFactory(23317): Unable to decode stream: java.io.FileNotFoundException: /storage/emulated/0/Pictures/myapp/IMG_20140714_191308.jpg: open failed: ENOENT (No such file or directory)
07-14 19:13:08.278: E/AndroidRuntime(23317): FATAL EXCEPTION: main
07-14 19:13:08.278: E/AndroidRuntime(23317): Process: com.domain.myapp, PID: 23317
07-14 19:13:08.278: E/AndroidRuntime(23317): java.lang.RuntimeException: Unable to resume activity {com.domain.myapp/com.domain.myapp.MainActivity}: java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=100, result=-1, data=null} to activity {com.domain.myapp/com.domain.myapp.MainActivity}: java.lang.NullPointerException
07-14 19:13:08.278: E/AndroidRuntime(23317):    at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2774)
07-14 19:13:08.278: E/AndroidRuntime(23317):    at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2803)
07-14 19:13:08.278: E/AndroidRuntime(23317):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2238)
07-14 19:13:08.278: E/AndroidRuntime(23317):    at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3724)
07-14 19:13:08.278: E/AndroidRuntime(23317):    at android.app.ActivityThread.access$900(ActivityThread.java:135)
07-14 19:13:08.278: E/AndroidRuntime(23317):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1202)
07-14 19:13:08.278: E/AndroidRuntime(23317):    at android.os.Handler.dispatchMessage(Handler.java:102)
07-14 19:13:08.278: E/AndroidRuntime(23317):    at android.os.Looper.loop(Looper.java:136)
07-14 19:13:08.278: E/AndroidRuntime(23317):    at android.app.ActivityThread.main(ActivityThread.java:5001)
07-14 19:13:08.278: E/AndroidRuntime(23317):    at java.lang.reflect.Method.invokeNative(Native Method)
07-14 19:13:08.278: E/AndroidRuntime(23317):    at java.lang.reflect.Method.invoke(Method.java:515)
07-14 19:13:08.278: E/AndroidRuntime(23317):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
07-14 19:13:08.278: E/AndroidRuntime(23317):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
07-14 19:13:08.278: E/AndroidRuntime(23317):    at dalvik.system.NativeStart.main(Native Method)
07-14 19:13:08.278: E/AndroidRuntime(23317): Caused by: java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=100, result=-1, data=null} to activity {com.domain.myapp/com.domain.myapp.MainActivity}: java.lang.NullPointerException
07-14 19:13:08.278: E/AndroidRuntime(23317):    at android.app.ActivityThread.deliverResults(ActivityThread.java:3351)
07-14 19:13:08.278: E/AndroidRuntime(23317):    at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2761)
07-14 19:13:08.278: E/AndroidRuntime(23317):    ... 13 more
07-14 19:13:08.278: E/AndroidRuntime(23317): Caused by: java.lang.NullPointerException
07-14 19:13:08.278: E/AndroidRuntime(23317):    at com.domain.myapp.MainActivity.draw_interface(MainActivity.java:97)
07-14 19:13:08.278: E/AndroidRuntime(23317):    at com.domain.myapp.MainActivity.draw(MainActivity.java:188)
07-14 19:13:08.278: E/AndroidRuntime(23317):    at com.domain.myapp.MainActivity.onActivityResult(MainActivity.java:234)
07-14 19:13:08.278: E/AndroidRuntime(23317):    at android.app.Activity.dispatchActivityResult(Activity.java:5423)
07-14 19:13:08.278: E/AndroidRuntime(23317):    at android.app.ActivityThread.deliverResults(ActivityThread.java:3347)
07-14 19:13:08.278: E/AndroidRuntime(23317):    ... 14 more

Answer 1

当屏幕在Create方法上旋转时，所有内容都将重新初始化，因此请确保您再次初始化所有变量并再次说明整个过程。

Answer 2

Rotating the screen will cause the Activity to be destroyed and created again, unless you specify otherwise.

To prevent that destruction and re-creation on screen rotate, add android:configChanges="orientation" to the Activitys entry in AndroidManifest. It will look something like this:

    <activity
        android:name="com.mpascual.example.IncallActivity"
        android:configChanges="orientation|keyboardHidden" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
        </intent-filter>
    </activity>

edit: I just added keyboardHidden to show you how you can set multiple values (in case you need it)