我知道之前已经问过这个问题，但他们的情况并不一样。
我的问题我需要使用PostPhotosActivity类retainInstance。我这样做的方式是把它变成一个片段。不幸的是，我总是收到这个错误。
12-13 14:38:55.669: E/AndroidRuntime(30234): FATAL EXCEPTION: main
12-13 14:38:55.669: E/AndroidRuntime(30234): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{trade.ly.tradely/trade.ly.tradely.PostPhotosActivity}: java.lang.ClassCastException: trade.ly.tradely.PostPhotosActivity cannot be cast to android.app.Activity
12-13 14:38:55.669: E/AndroidRuntime(30234): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2106)
12-13 14:38:55.669: E/AndroidRuntime(30234): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
12-13 14:38:55.669: E/AndroidRuntime(30234): at android.app.ActivityThread.access$600(ActivityThread.java:141)
12-13 14:38:55.669: E/AndroidRuntime(30234): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
12-13 14:38:55.669: E/AndroidRuntime(30234): at android.os.Handler.dispatchMessage(Handler.java:99)
12-13 14:38:55.669: E/AndroidRuntime(30234): at android.os.Looper.loop(Looper.java:137)
12-13 14:38:55.669: E/AndroidRuntime(30234): at android.app.ActivityThread.main(ActivityThread.java:5039)
12-13 14:38:55.669: E/AndroidRuntime(30234): at java.lang.reflect.Method.invokeNative(Native Method)
12-13 14:38:55.669: E/AndroidRuntime(30234): at java.lang.reflect.Method.invoke(Method.java:511)
12-13 14:38:55.669: E/AndroidRuntime(30234): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
12-13 14:38:55.669: E/AndroidRuntime(30234): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
12-13 14:38:55.669: E/AndroidRuntime(30234): at dalvik.system.NativeStart.main(Native Method)
12-13 14:38:55.669: E/AndroidRuntime(30234): Caused by: java.lang.ClassCastException: trade.ly.tradely.PostPhotosActivity cannot be cast to android.app.Activity
12-13 14:38:55.669: E/AndroidRuntime(30234): at android.app.Instrumentation.newActivity(Instrumentation.java:1054)
12-13 14:38:55.669: E/AndroidRuntime(30234): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2097)
12-13 14:38:55.669: E/AndroidRuntime(30234): ... 11 more
这是造成所有错误的PostPhotosActivity。
public class PostPhotosActivity extends android.app.Fragment {
public static final String TAG = "PostPhotosActivity";
String title, price, description, maincat, subcat, pname, pemail, pphone, pmeet, imageUri;
public static final String TEMP_PHOTO_FILE_NAME = "temp_photo.jpg";
public static final int REQUEST_CODE_GALLERY = 0x1;
public static final int REQUEST_CODE_TAKE_PICTURE = 0x2;
public static final int REQUEST_CODE_CROP_IMAGE = 0x3;
private ImageView mImageView;
private File mFileTemp;
ParseFile file;
double latitude;
final String[] items = new String[] { "Take from camera", "Select from gallery" };
double longitude;
Button button;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.activity_post_photos, container,false);
Bundle extras= getActivity().getIntent().getExtras();
if(extras!=null)
{
title = extras.getString("TITLE"); // get the value based on the key
price = extras.getString("PRICE"); // get the value based on the key
description = extras.getString("DESCRIPTION"); // get the value based on the key
maincat = extras.getString("MAINCAT"); // get the value based on the key
subcat = extras.getString("SUBCAT"); // get the value based on the key
pname = extras.getString("PNAME"); // get the value based on the key
pemail = extras.getString("PEMAIL"); // get the value based on the key
pphone = extras.getString("PPHONE"); // get the value based on the key
pmeet = extras.getString("PMEET"); // get the value based on the key
latitude = extras.getDouble("lat");
longitude = extras.getDouble("long");
}
Button newPost = (Button)view.findViewById(R.id.post_data);
newPost.setVisibility(View.INVISIBLE);
newPost.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// Perform action on click
ParseGeoPoint point = new ParseGeoPoint(latitude, longitude);
ParseObject setPost = new ParseObject("Posts");
// Create an author relationship with the current user
setPost.put("author", ParseUser.getCurrentUser());
// Get location
setPost.put("location", point);
setPost.put("Title", title);
setPost.put("Price", price);
setPost.put("Description", description);
setPost.put("MainCat", maincat);
setPost.put("SubCat", subcat);
setPost.put("PName", pname);
setPost.put("PEmail", pemail);
setPost.put("PPhone", pphone);
setPost.put("PMeet", pmeet);
setPost.put("Photo", file);
setPost.saveInBackground();
Intent intent = new Intent(getActivity(), Flow.class);
startActivity(intent);
}
});
ArrayAdapter<String> adapter = new ArrayAdapter<String>(getActivity(), android.R.layout.select_dialog_item, items);
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setTitle("Select Image");
builder.setAdapter(adapter, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int item) { // pick from
// camera
if (item == 0) {
takePicture();
} else { // pick from file
openGallery();
}
}
});
final AlertDialog dialog = builder.create();
mImageView = (ImageView) view.findViewById(R.id.iv_photo);
mImageView.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
dialog.show();
}
});
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state)) {
mFileTemp = new File(Environment.getExternalStorageDirectory(), TEMP_PHOTO_FILE_NAME);
}
else {
mFileTemp = new File(getActivity().getFilesDir(), TEMP_PHOTO_FILE_NAME);
}
setRetainInstance(true);
return view;
}
private void takePicture() {
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
try {
Uri mImageCaptureUri = null;
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state)) {
mImageCaptureUri = Uri.fromFile(mFileTemp);
}
else {
/*
* The solution is taken from here: http://stackoverflow.com/questions/10042695/how-to-get-camera-result-as-a-uri-in-data-folder
*/
mImageCaptureUri = InternalStorageContentProvider.CONTENT_URI;
}
intent.putExtra(android.provider.MediaStore.EXTRA_OUTPUT, mImageCaptureUri);
intent.putExtra("return-data", true);
startActivityForResult(intent, REQUEST_CODE_TAKE_PICTURE);
} catch (ActivityNotFoundException e) {
Log.d(TAG, "cannot take picture", e);
}
}
private void openGallery() {
Intent photoPickerIntent = new Intent(Intent.ACTION_PICK);
photoPickerIntent.setType("image/*");
startActivityForResult(photoPickerIntent, REQUEST_CODE_GALLERY);
}
private void startCropImage() {
Intent intent = new Intent(getActivity(), CropImage.class);
intent.putExtra(CropImage.IMAGE_PATH, mFileTemp.getPath());
intent.putExtra(CropImage.SCALE, true);
intent.putExtra(CropImage.ASPECT_X, 1);
intent.putExtra(CropImage.ASPECT_Y, 1);
startActivityForResult(intent, REQUEST_CODE_CROP_IMAGE);
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (resultCode != Activity.RESULT_OK) {
return;
}
Bitmap bitmap;
switch (requestCode) {
case REQUEST_CODE_GALLERY:
try {
InputStream inputStream = getActivity().getContentResolver().openInputStream(data.getData());
FileOutputStream fileOutputStream = new FileOutputStream(mFileTemp);
copyStream(inputStream, fileOutputStream);
fileOutputStream.close();
inputStream.close();
startCropImage();
} catch (Exception e) {
Log.e(TAG, "Error while creating temp file", e);
}
break;
case REQUEST_CODE_TAKE_PICTURE:
startCropImage();
break;
case REQUEST_CODE_CROP_IMAGE:
String path = data.getStringExtra(CropImage.IMAGE_PATH);
if (path == null) {
return;
}
//byte[] idata = path.getBytes();
Bitmap picture = BitmapFactory.decodeFile(path);
ByteArrayOutputStream stream = new ByteArrayOutputStream();
picture.compress(Bitmap.CompressFormat.JPEG, 100, stream);
// get byte array here
byte[] idata= stream.toByteArray();
file = new ParseFile("photo.jpg", idata);
file.saveInBackground();
bitmap = BitmapFactory.decodeFile(mFileTemp.getPath());
mImageView.setImageBitmap(bitmap);
button.setVisibility(View.VISIBLE);
break;
}
super.onActivityResult(requestCode, resultCode, data);
}
public static void copyStream(InputStream input, OutputStream output)
throws IOException {
byte[] buffer = new byte[1024];
int bytesRead;
while ((bytesRead = input.read(buffer)) != -1) {
output.write(buffer, 0, bytesRead);
}
}
}
清单
<activity
android:name="trade.ly.tradely.PostPhotosActivity"
android:label="@string/title_activity_post_photos">
</activity>
在“点击”
上创建片段的类活动 public class PostActivity extends FragmentActivity implements
PageFragmentCallbacks, ReviewFragment.Callbacks, ModelCallbacks {
private ViewPager mPager;
private MyPagerAdapter mPagerAdapter;
private boolean mEditingAfterReview;
private AbstractWizardModel mWizardModel = new SandwichWizardModel(this);
private boolean mConsumePageSelectedEvent;
private Button mNextButton;
private Button mPrevButton;
String user_name;
String uemail;
private List<Page> mCurrentPageSequence;
private StepPagerStrip mStepPagerStrip;
public static final String TAG = "PostActivity";
double latitude, longitude;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_post);
Bundle extras = getIntent().getExtras();
if(extras !=null) {
// Get the results
user_name = extras.getString("name");
uemail = extras.getString("email");
}
Bundle data = new Bundle();
if (!TextUtils.isEmpty(CustomerInfoPage.EMAIL_DATA_KEY)) {
data.putString(CustomerInfoPage.EMAIL_DATA_KEY, uemail);
mWizardModel.findByKey("Your Info").resetData(data);
}
GpsLocationTracker mGpsLocationTracker = new GpsLocationTracker(PostActivity.this);
// Set GPS Location fetched address
if (mGpsLocationTracker.canGetLocation())
{
latitude = mGpsLocationTracker.getLatitude();
longitude = mGpsLocationTracker.getLongitude();
Log.i(TAG, String.format("latitude: %s", latitude));
Log.i(TAG, String.format("longitude: %s", longitude));
}
else
{
mGpsLocationTracker.showSettingsAlert();
}
if (savedInstanceState != null) {
mWizardModel.load(savedInstanceState.getBundle("model"));
}
mWizardModel.registerListener(this);
mPagerAdapter = new MyPagerAdapter(getSupportFragmentManager());
mPager = (ViewPager) findViewById(R.id.pager);
mPager.setAdapter(mPagerAdapter);
mStepPagerStrip = (StepPagerStrip) findViewById(R.id.strip);
mStepPagerStrip.setOnPageSelectedListener(new StepPagerStrip.OnPageSelectedListener() {
@Override
public void onPageStripSelected(int position) {
position = Math.min(mPagerAdapter.getCount() - 1, position);
if (mPager.getCurrentItem() != position) {
mPager.setCurrentItem(position);
}
}
});
mNextButton = (Button) findViewById(R.id.next_button);
mPrevButton = (Button) findViewById(R.id.prev_button);
mPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
@Override
public void onPageSelected(int position) {
mStepPagerStrip.setCurrentPage(position);
if (mConsumePageSelectedEvent) {
mConsumePageSelectedEvent = false;
return;
}
mEditingAfterReview = false;
updateBottomBar();
}
});
mNextButton.setOnClickListener(new View.OnClickListener() {
@SuppressLint("ValidFragment")
@Override
public void onClick(View view) {
if (mPager.getCurrentItem() == mCurrentPageSequence.size()) {
DialogFragment dg = new DialogFragment() {
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
return new AlertDialog.Builder(getActivity())
.setMessage(R.string.submit_confirm_message)
.setPositiveButton(
R.string.submit_confirm_button,
new DialogInterface.OnClickListener() {
public void onClick(
DialogInterface dialog,
int id) {
String title = mWizardModel
.findByKey(
"Post Info")
.getData()
.getString(
TpdModel.TITLE_DATA_KEY);
String price = mWizardModel
.findByKey(
"Post Info")
.getData()
.getString(
TpdModel.PRICE_DATA_KEY);
String description = mWizardModel
.findByKey(
"Post Info")
.getData()
.getString(
TpdModel.DESCRIPTION_DATA_KEY);
String maincat = mWizardModel
.findByKey(
"Main Category")
.getData()
.getString(
Page.SIMPLE_DATA_KEY);
String subcat = mWizardModel
.findByKey(
"Sub Category")
.getData()
.getString(
Page.SIMPLE_DATA_KEY);
String pname = mWizardModel
.findByKey(
"Your Info")
.getData()
.getString(
CustomerInfoPage.NAME_DATA_KEY);
String pemail = mWizardModel
.findByKey(
"Your Info")
.getData()
.getString(
CustomerInfoPage.EMAIL_DATA_KEY);
String pphone = mWizardModel
.findByKey(
"Your Info")
.getData()
.getString(
CustomerInfoPage.PHONE_DATA_KEY);
String pmeet = mWizardModel
.findByKey(
"Your Info")
.getData()
.getString(
CustomerInfoPage.MEET_DATA_KEY);
Intent i = new Intent(
PostActivity.this,
PostPhotosActivity.class);
i.putExtra("TITLE", title);
i.putExtra("PRICE", price);
i.putExtra("DESCRIPTION",
description);
i.putExtra("MAINCAT",
maincat);
i.putExtra("SUBCAT", subcat);
i.putExtra("PNAME", pname);
i.putExtra("PEMAIL", pemail);
i.putExtra("PPHONE", pphone);
i.putExtra("PMEET", pmeet);
i.putExtra("lat", latitude);
i.putExtra("long", longitude);
startActivityForResult(i, 0);
}
})
.setNegativeButton(android.R.string.cancel,
null).create();
}
};
dg.show(getSupportFragmentManager(), "place_order_dialog");
} else {
if (mEditingAfterReview) {
mPager.setCurrentItem(mPagerAdapter.getCount() - 1);
} else {
mPager.setCurrentItem(mPager.getCurrentItem() + 1);
}
}
}
});
mPrevButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
mPager.setCurrentItem(mPager.getCurrentItem() - 1);
}
});
onPageTreeChanged();
updateBottomBar();
}
@Override
public void onPageTreeChanged() {
mCurrentPageSequence = mWizardModel.getCurrentPageSequence();
recalculateCutOffPage();
mStepPagerStrip.setPageCount(mCurrentPageSequence.size() + 1); // + 1 =
// review
// step
mPagerAdapter.notifyDataSetChanged();
updateBottomBar();
}
private void updateBottomBar() {
int position = mPager.getCurrentItem();
if (position == mCurrentPageSequence.size()) {
mNextButton.setText(R.string.finish);
mNextButton.setBackgroundResource(R.drawable.finish_background);
mNextButton.setTextAppearance(this, R.style.TextAppearanceFinish);
} else {
mNextButton.setText(mEditingAfterReview ? R.string.review
: R.string.next);
mNextButton
.setBackgroundResource(R.drawable.selectable_item_background);
TypedValue v = new TypedValue();
getTheme().resolveAttribute(android.R.attr.textAppearanceMedium, v,
true);
mNextButton.setTextAppearance(this, v.resourceId);
mNextButton.setEnabled(position != mPagerAdapter.getCutOffPage());
}
mPrevButton
.setVisibility(position <= 0 ? View.INVISIBLE : View.VISIBLE);
}
@Override
protected void onDestroy() {
super.onDestroy();
mWizardModel.unregisterListener(this);
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putBundle("model", mWizardModel.save());
}
@Override
public AbstractWizardModel onGetModel() {
return mWizardModel;
}
@Override
public void onEditScreenAfterReview(String key) {
for (int i = mCurrentPageSequence.size() - 1; i >= 0; i--) {
if (mCurrentPageSequence.get(i).getKey().equals(key)) {
mConsumePageSelectedEvent = true;
mEditingAfterReview = true;
mPager.setCurrentItem(i);
updateBottomBar();
break;
}
}
}
@Override
public void onPageDataChanged(Page page) {
if (page.isRequired()) {
if (recalculateCutOffPage()) {
mPagerAdapter.notifyDataSetChanged();
updateBottomBar();
}
}
}
@Override
public Page onGetPage(String key) {
return mWizardModel.findByKey(key);
}
private boolean recalculateCutOffPage() {
// Cut off the pager adapter at first required page that isn't completed
int cutOffPage = mCurrentPageSequence.size() + 1;
for (int i = 0; i < mCurrentPageSequence.size(); i++) {
Page page = mCurrentPageSequence.get(i);
if (page.isRequired() && !page.isCompleted()) {
cutOffPage = i;
break;
}
}
if (mPagerAdapter.getCutOffPage() != cutOffPage) {
mPagerAdapter.setCutOffPage(cutOffPage);
return true;
}
return false;
}
public class MyPagerAdapter extends FragmentStatePagerAdapter {
private int mCutOffPage;
private Fragment mPrimaryItem;
public MyPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int i) {
if (i >= mCurrentPageSequence.size()) {
return new ReviewFragment();
}
return mCurrentPageSequence.get(i).createFragment();
}
@Override
public int getItemPosition(Object object) {
// TODO: be smarter about this
if (object == mPrimaryItem) {
// Re-use the current fragment (its position never changes)
return POSITION_UNCHANGED;
}
return POSITION_NONE;
}
@Override
public void setPrimaryItem(ViewGroup container, int position,
Object object) {
super.setPrimaryItem(container, position, object);
mPrimaryItem = (Fragment) object;
}
@Override
public int getCount() {
return Math.min(mCutOffPage + 1, mCurrentPageSequence == null ? 1
: mCurrentPageSequence.size() + 1);
}
public void setCutOffPage(int cutOffPage) {
if (cutOffPage < 0) {
cutOffPage = Integer.MAX_VALUE;
}
mCutOffPage = cutOffPage;
}
public int getCutOffPage() {
return mCutOffPage;
}
}
}
答案 0 :(得分：3)
您不能将PostPhotosActivity用作活动，因为它不是活动。它是片段，因为它扩展Fragment而不是Activity。在你的清单中使用它是一个错误，并在intent
Intent i = new Intent(
PostActivity.this,
PostPhotosActivity.class);
导致出现异常，因为Fragment无法投放到Activity。
您可以在其他一些活动中将此片段与xml布局一起使用，或将片段更改为activity。 xml布局示例：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="match_parent" android:layout_height="match_parent">
<fragment class="com.example.PostPhotosFragment"
android:id="@+id/post_photos_fragment"
android:layout_width="match_parent" android:layout_height="match_parent" />
</LinearLayout>
然后在一些扩展Activity课程调用setContentView(R.layout.yourlayout)的活动中，您的片段将在您的活动中创建。