片段不能转换为 android.app.activity
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【中文标题】片段不能转换为 android.app.activity【英文标题】：Fragment cannot be cast to android.app.activity 【发布时间】：2014-01-01 19:50:18 【问题描述】：我知道以前有人问过这个问题，但他们的情况与我不同。
我的问题是我的 PostPhotosActivity 类需要保留实例。我这样做的方式是将它变成一个片段。不幸的是，我总是遇到这个错误。
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 ComponentInfotrade.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
这是导致所有错误的 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://***.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>
在点击时创建片段的类 Activity
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;
【问题讨论】：
请发布整个堆栈跟踪。 请在创建或使用 PostPhotosActivity 类（清单或代码中的某处）时发布代码片段。片段不是一个活动，我认为你正试图在需要活动的地方使用这个片段。 请检查编辑！ 【参考方案1】：您不能将PostPhotosActivity 用作活动，因为它不是活动。它是片段，因为它扩展了Fragment 而不是Activity。在你的清单中有这个是一个错误，并在意图上调用 startActivityForResult
Intent i = new Intent(
PostActivity.this,
PostPhotosActivity.class);
导致转换异常，因为 Fragment 无法转换为 Activity。
您可以在其他活动中使用带有此片段的 xml 布局或将片段更改为活动。 xml布局示例：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_ android:layout_>
<fragment class="com.example.PostPhotosFragment"
android:id="@+id/post_photos_fragment"
android:layout_ android:layout_ />
</LinearLayout>
然后在扩展Activity 类的一些活动中调用setContentView(R.layout.yourlayout)，您的片段将在您的活动中创建。
【讨论】：
非常感谢！我试图解决的实际问题并没有解决，但这个问题已经解决了。以上是关于片段不能转换为 android.app.activity的主要内容，如果未能解决你的问题，请参考以下文章
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