Android 旋转设备后从DialogFragment接收回调时,片段未附加到活动
我正在创建一个应用程序,允许用户从图库上传图像或使用设备摄像头拍照。单击相应按钮时,会出现一个对话框,用户可以选择“拍照”或“选择图像”。这一切都很好,问题是当我在屏幕上显示对话框时旋转设备,然后选择一个选项,应用程序会崩溃,出现Android 旋转设备后从DialogFragment接收回调时,片段未附加到活动,android,android-fragments,Android,Android Fragments,我正在创建一个应用程序,允许用户从图库上传图像或使用设备摄像头拍照。单击相应按钮时,会出现一个对话框,用户可以选择“拍照”或“选择图像”。这一切都很好,问题是当我在屏幕上显示对话框时旋转设备,然后选择一个选项,应用程序会崩溃,出现IllegalStateException,表示我的片段未连接到活动。我已经包含了用于与目标片段通信的对话框: 创建对话框片段: public void onClick() { // Display a Dialog for choice between pic
IllegalStateException
,表示我的片段未连接到活动。我已经包含了用于与目标片段通信的对话框:
创建对话框片段:
public void onClick() {
// Display a Dialog for choice between pick/ take picture
ListDialogFragment dialogFragment = ListDialogFragment.newInstance(R.string.take_photo, R.array.add_picture_options_array);
dialogFragment.setTargetFragment(this, 0);
dialogFragment.show(getFragmentManager(), "Moo");
}
DialogFragment类:
public class ListDialogFragment extends DialogFragment {
private static final String TITLE_RESOURCE_ID = "title_resource_id";
private static final String ARRAY_RESOURCE_ID = "array_resource_id";
private DialogItemSelectedListener listener;
public interface DialogItemSelectedListener {
void onTakePhotoSelected();
void onSelectImageSelected();
}
public ListDialogFragment() {
// Default empty constructor
}
public static ListDialogFragment newInstance(@StringRes final int titleResourceId, @ArrayRes final int arrayResourceId) {
ListDialogFragment dialogFragment = new ListDialogFragment();
Bundle bundle = new Bundle();
bundle.putInt(TITLE_RESOURCE_ID, titleResourceId);
bundle.putInt(ARRAY_RESOURCE_ID, arrayResourceId);
dialogFragment.setArguments(bundle);
return dialogFragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
try {
listener = (DialogItemSelectedListener) getTargetFragment();
} catch (ClassCastException e) {
throw new ClassCastException("Calling Fragment must implement DialogItemSelectedListener");
}
}
@NonNull
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
final int title = getArguments().getInt(TITLE_RESOURCE_ID);
final int listItems = getArguments().getInt(ARRAY_RESOURCE_ID);
return new AlertDialog.Builder(getActivity()).setTitle(title).setItems(listItems, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
switch (which) {
case 0:
listener.onTakePhotoSelected();
break;
case 1:
listener.onSelectImageSelected();
break;
default:
dismiss();
}
}
}).create();
}
}
片段实现了对话框ItemSelectedListener
,并在调用onTakePhotoSelected()
时尝试执行以下操作:
private void takePicture() {
Intent cameraIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
// Here, we make sure that an Activity to handle the Camera Intent actually exists
if (cameraIntent.resolveActivity(context.getApplicationContext().getPackageManager()) != null) {
// This is where the photo itself will actually go
imageFile = null;
try {
imageFile = createImageFile();
} catch (IOException ex) {
// Could not create the file
}
// At this point, we can safely assume that the file was created successfully
if (imageFile != null) {
cameraIntent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(imageFile));
startActivityForResult(cameraIntent, REQUEST_IMAGE_CAPTURE);
}
}
}
活动:
public class TestActivity extends ActionBarActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.test_activity);
attachFragment();
}
private void attachFragment() {
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, TestFragment.newInstance()).commit();
}
}
调用startActivityForResult()时应用程序崩溃代码>
我在这里做错了什么;这种行为是意料之中的吗?
我已经尝试了setRetainInstance(true)代码>但这不起作用。这里的问题是,每次方向改变时,您都在创建一个新的片段实例。实际上,只有其中一个与活动相关。试试这个
public class TestActivity extends ActionBarActivity {
TestFragment testFragment;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.test_activity);
attachFragment(savedInstanceState);
}
private void attachFragment(Bundle savedInstanceState) {
if (savedInstanceState == null) {
testFragment = TestFragment.newInstance();
getSupportFragmentManager().beginTransaction()
.replace(R.id.fragment_container, testFragment, "testFragment").commit();
} else {
testFragment = (TestFragment) getSupportFragmentManager().findFragmentByTag("testFragment");
}
}
这里的问题是,每次方向改变时,您都在创建一个新的Fragment实例。实际上,只有其中一个与活动相关。试试这个
public class TestActivity extends ActionBarActivity {
TestFragment testFragment;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.test_activity);
attachFragment(savedInstanceState);
}
private void attachFragment(Bundle savedInstanceState) {
if (savedInstanceState == null) {
testFragment = TestFragment.newInstance();
getSupportFragmentManager().beginTransaction()
.replace(R.id.fragment_container, testFragment, "testFragment").commit();
} else {
testFragment = (TestFragment) getSupportFragmentManager().findFragmentByTag("testFragment");
}
}
使用getChildFragmentManager()
代替getFragmentManager()
李>
不要使用setTargetFragment()
和getTargetFragment()
,而是在对话框Fragment中使用getParentFragment()
这在我的例子中是有效的,但我应该注意,我只使用片段的onActivityResult()
方法将值传递给片段
使用getChildFragmentManager()
代替getFragmentManager()
李>
不要使用setTargetFragment()
和getTargetFragment()
,而是在对话框Fragment中使用getParentFragment()
这在我的情况下是有效的,但我应该注意,我只使用片段的onActivityResult()
方法将值传递给片段。尝试将getFragmentManager()
更改为getChildFragmentManager
,因为您是从片段内部而不是从活动打开对话框的。尝试更改getFragmentManager()
到getChildFragmentManager
,因为您是从片段而不是从活动中打开对话框的。