这是完整的日志
11-16 04:13:35.810 3555-3555/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.steven.test, PID: 3555
java.lang.ClassCastException: com.steven.test.MainActivity cannot be cast to com.steven.test.providers.priceticker.currencylist.AllCurrencyListFragment$FavoritesListUpdater
at com.steven.test.providers.priceticker.currencylist.AllCurrencyListFragment.onAttach(AllCurrencyListFragment.java:182)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1372)
at android.support.v4.app.FragmentTransition.addToFirstInLastOut(FragmentTransition.java:1188)
at android.support.v4.app.FragmentTransition.calculateFragments(FragmentTransition.java:1071)
at android.support.v4.app.FragmentTransition.startTransitions(FragmentTransition.java:115)
at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2380)
at android.support.v4.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManager.java:2338)
at android.support.v4.app.FragmentManagerImpl.execSingleAction(FragmentManager.java:2215)
at android.support.v4.app.BackStackRecord.commitNowAllowingStateLoss(BackStackRecord.java:649)
at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:145)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1238)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1086)
at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1616)
at android.view.View.measure(View.java:22091)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6602)
at android.support.design.widget.CoordinatorLayout.onMeasureChild(CoordinatorLayout.java:739)
at android.support.design.widget.HeaderScrollingViewBehavior.onMeasureChild(HeaderScrollingViewBehavior.java:91)
at android.support.design.widget.AppBarLayout$ScrollingViewBehavior.onMeasureChild(AppBarLayout.java:1361)
at android.support.design.widget.CoordinatorLayout.onMeasure(CoordinatorLayout.java:809)
at android.view.View.measure(View.java:22091)
at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1632)
at com.duolingo.open.rtlviewpager.RtlViewPager.onMeasure(RtlViewPager.java:211)
at android.view.View.measure(View.java:22091)
at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:715)
at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:461)
at android.view.View.measure(View.java:22091)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6602)
at android.support.design.widget.CoordinatorLayout.onMeasureChild(CoordinatorLayout.java:739)
at android.support.design.widget.HeaderScrollingViewBehavior.onMeasureChild(HeaderScrollingViewBehavior.java:91)
at android.support.design.widget.AppBarLayout$ScrollingViewBehavior.onMeasureChild(AppBarLayout.java:1361)
at android.support.design.widget.CoordinatorLayout.onMeasure(CoordinatorLayout.java:809)
at android.view.View.measure(View.java:22091)
at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:715)
at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:461)
at android.view.View.measure(View.java:22091)
at android.support.v4.widget.DrawerLayout.onMeasure(DrawerLayout.java:1059)
at android.view.View.measure(View.java:22091)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6602)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:141)
at android.view.View.measure(View.java:22091)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6602)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
at android.view.View.measure(View.java:22091)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6602)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
at android.view.View.measure(View.java:22091)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6602)
11-16 04:13:35.811 3555-3555/? E/AndroidRuntime: at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1514)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:806)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:685)
at android.view.View.measure(View.java:22091)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6602)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
at com.android.internal.policy.DecorView.onMeasure(DecorView.java:725)
at android.view.View.measure(View.java:22091)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2447)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1529)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1786)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1417)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6934)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:979)
at android.view.Choreographer.doCallbacks(Choreographer.java:791)
at android.view.Choreographer.doFrame(Choreographer.java:726)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:965)
at android.os.Handler.handleCallback(Handler.java:790)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6578)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:460)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
这是我的活动：
开始并传递到另一个片段的片段-
public class CurrencyListTabsFragment extends Fragment implements ViewPager.OnPageChangeListener,
FavoriteCurrencyListFragment.AllCoinsListUpdater, AllCurrencyListFragment.FavoritesListUpdater {
private SectionsPagerAdapterCurrencyList mSectionsPagerAdapter;
private View rootView;
public ViewPager mViewPager;
public static String baseImageURL = "";
public static String SYMBOL = "SYMBOL";
private Toolbar mToolbar;
public final static String DAY = "24h";
public final static String WEEK = "7d";
public final static String HOUR = "1h";
public final static String SORT_SETTING = "sort_setting";
public Fragment context;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.activity_currency_list_tabs, container, false);
context = this;
mToolbar = rootView.findViewById(R.id.toolbar_currency_list);
((AppCompatActivity)getActivity()).setSupportActionBar(mToolbar);
TabLayout tabLayout = rootView.findViewById(R.id.currency_list_tabs);
mViewPager = rootView.findViewById(R.id.currency_list_tabs_container);
mSectionsPagerAdapter = new SectionsPagerAdapterCurrencyList(getActivity().getSupportFragmentManager());
mViewPager.setAdapter(mSectionsPagerAdapter);
mViewPager.setOffscreenPageLimit(2);
mViewPager.addOnPageChangeListener(this);
tabLayout.setupWithViewPager(mViewPager);
tabLayout.setSelectedTabIndicatorColor(Color.WHITE);
return rootView;
}
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
Fragment fragment = mSectionsPagerAdapter.getFragment(position);
if (fragment != null) {
fragment.onResume();
}
}
@Override
public void onPageScrollStateChanged(int state) {
}
public void removeFavorite(CMCCoin coin) {
FavoriteCurrencyListFragment frag = (FavoriteCurrencyListFragment) mSectionsPagerAdapter.getFragment(1);
if (frag != null) {
frag.removeFavorite(coin);
}
}
public void addFavorite(CMCCoin coin) {
FavoriteCurrencyListFragment frag = (FavoriteCurrencyListFragment) mSectionsPagerAdapter.getFragment(1);
if (frag != null) {
frag.addFavorite(coin);
}
}
public void allCoinsModifyFavorites(CMCCoin coin) {
AllCurrencyListFragment frag = (AllCurrencyListFragment) mSectionsPagerAdapter.getFragment(0);
if (frag != null) {
frag.getAdapter().notifyDataSetChanged();
}
}
public void performFavsSort() {
FavoriteCurrencyListFragment frag = (FavoriteCurrencyListFragment) mSectionsPagerAdapter.getFragment(1);
if (frag != null) {
frag.performFavsSort();
}
}
public void performAllCoinsSort() {
AllCurrencyListFragment frag = (AllCurrencyListFragment) mSectionsPagerAdapter.getFragment(0);
if (frag != null) {
frag.performAllCoinsSort();
}
}
}
这是在“ onAttach”方法中引发错误的片段
public class AllCurrencyListFragment extends Fragment implements SwipeRefreshLayout.OnRefreshListener,
SearchView.OnQueryTextListener {
private SwipeRefreshLayout swipeRefreshLayout;
private RecyclerView currencyRecyclerView;
private AllCurrencyListAdapter adapter;
private ArrayList<CMCCoin> currencyItemList;
private ArrayList<CMCCoin> filteredList = new ArrayList<>();
private MenuItem searchItem;
private SearchView searchView;
private View rootView;
private Context mContext;
public static String currQuery = "";
ArrayList<CMCCoin> searchList;
private HashMap<String, String> searchedSymbols = new HashMap<>();
private HashMap<String, Integer> slugToIDMap = new HashMap<>();
public static boolean searchViewFocused = false;
private FavoritesListUpdater favsUpdateCallback;
private SharedPreferences sharedPreferences;
public interface FavoritesListUpdater {
void removeFavorite(CMCCoin coin);
void addFavorite(CMCCoin coin);
void performFavsSort();
}
public AllCurrencyListFragment() {
}
public void performAllCoinsSort() {
int sortType = sharedPreferences.getInt(SORT_SETTING, 1);
sortList(adapter.getCurrencyList(), sortType);
adapter.notifyDataSetChanged();
}
public void getQuickSearch() {
CoinMarketCapService.getCMCQuickSearch(mContext, new afterTaskCompletion<CMCQuickSearch[]>() {
@Override
public void onTaskCompleted(CMCQuickSearch[] quickSearchNodeList) {
slugToIDMap = new HashMap<>();
Parcelable recyclerViewState;
recyclerViewState = currencyRecyclerView.getLayoutManager().onSaveInstanceState();
for (CMCQuickSearch node : quickSearchNodeList) {
slugToIDMap.put(node.getSlug(), node.getId());
}
if (searchViewFocused) {
for (CMCCoin coin: searchList) {
if (slugToIDMap.get(coin.getId()) != null) {
coin.setQuickSearchID(slugToIDMap.get(coin.getId()));
}
}
adapter.setCurrencyList(searchList);
} else {
for (CMCCoin coin : currencyItemList) {
if (coin.getId() != null && slugToIDMap.get(coin.getId()) != null) {
coin.setQuickSearchID(slugToIDMap.get(coin.getId()));
}
}
adapter.setCurrencyList(currencyItemList);
}
int sortType = sharedPreferences.getInt(SORT_SETTING, 1);
sortList(adapter.getCurrencyList(), sortType);
adapter.notifyDataSetChanged();
favsUpdateCallback.performFavsSort();
currencyRecyclerView.getLayoutManager().onRestoreInstanceState(recyclerViewState);
swipeRefreshLayout.setRefreshing(false);
}
}, new afterTaskFailure() {
@Override
public void onTaskFailed(Object o, Exception e) {
Log.e("ERROR", "Server Error: " + e.getMessage());
swipeRefreshLayout.setRefreshing(false);
}
}, true);
}
@Override
public void onRefresh() {
getCurrencyList();
}
public static AllCurrencyListFragment newInstance() {
return new AllCurrencyListFragment();
}
public void getCurrencyList() {
swipeRefreshLayout.setRefreshing(true);
CoinMarketCapService.getAllCoins(mContext, new afterTaskCompletion<CMCCoin[]>() {
@Override
public void onTaskCompleted(CMCCoin[] cmcCoinList) {
try {
if (searchViewFocused) { // Copy some code here to make the checks faster
searchedSymbols.clear();
searchList.clear();
for (CMCCoin coin : filteredList) {
searchedSymbols.put(coin.getSymbol(), coin.getSymbol());
}
for (CMCCoin coin : cmcCoinList) {
if (searchedSymbols.get(coin.getSymbol()) != null) {
searchList.add(coin);
}
}
} else {
currencyItemList.clear();
currencyItemList.addAll(Arrays.asList(cmcCoinList));
}
} catch (Exception e) {
e.printStackTrace();
}
getQuickSearch();
}
}, new afterTaskFailure() {
@Override
public void onTaskFailed(Object o, Exception e) {
Log.e("ERROR", "Server Error: " + e.getMessage());
swipeRefreshLayout.setRefreshing(false);
}
}, true);
}
@Override
public void onResume() {
super.onResume();
getActivity().invalidateOptionsMenu();
}
@Override
public void onAttach(Context context) {
this.mContext = context;
this.favsUpdateCallback = (FavoritesListUpdater) context;
super.onAttach(context);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.fragment_all_currency_list, container, false);
setHasOptionsMenu(true);
DatabaseHelperSingleton db = DatabaseHelperSingleton.getInstance(mContext);
sharedPreferences = getContext().getSharedPreferences(SHAREDPREF_SETTINGS, MODE_PRIVATE);
searchList = new ArrayList<>();
// Setup currency list
currencyRecyclerView = rootView.findViewById(R.id.currency_list_recycler_view);
HorizontalDividerItemDecoration divider = new HorizontalDividerItemDecoration.Builder(mContext).build();
currencyRecyclerView.addItemDecoration(divider);
LinearLayoutManager llm = new LinearLayoutManager(mContext);
llm.setOrientation(LinearLayoutManager.VERTICAL);
currencyRecyclerView.setLayoutManager(llm);
currencyItemList = new ArrayList<>();
adapter = new AllCurrencyListAdapter(favsUpdateCallback, currencyItemList, db, (AppCompatActivity) mContext, new CustomItemClickListener() {
@Override
public void onItemClick(int position, View v) {
Intent intent = new Intent(mContext, CurrencyDetailsTabsActivity.class);
intent.putExtra(GraphFragment.ARG_SYMBOL, adapter.getCurrencyList().get(position).getSymbol());
intent.putExtra(GraphFragment.ARG_ID, adapter.getCurrencyList().get(position).getId());
intent.putExtra(GraphFragment.COIN_OBJECT, adapter.getCurrencyList().get(position));
mContext.startActivity(intent);
}
});
currencyRecyclerView.setAdapter(adapter);
// Setup swipe refresh layout
swipeRefreshLayout = rootView.findViewById(R.id.currency_list_swipe_refresh);
swipeRefreshLayout.setColorSchemeResources(R.color.myAccentColor);
swipeRefreshLayout.setOnRefreshListener(this);
swipeRefreshLayout.post(new Runnable() {
@Override
public void run() {
swipeRefreshLayout.setRefreshing(true);
getCurrencyList();
}
});
return rootView;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch(item.getItemId()) {
case R.id.sort_button:
int sortType = sharedPreferences.getInt(SORT_SETTING, 1);
new MaterialDialog.Builder(getActivity())
.title(R.string.sort_by)
.items(R.array.sort_options)
.dividerColorRes(R.color.myPrimaryColor)
.widgetColorRes(R.color.myPrimaryColor)
.buttonRippleColorRes(R.color.myPrimaryColor)
.itemsCallbackSingleChoice(sortType, new MaterialDialog.ListCallbackSingleChoice() {
@Override
public boolean onSelection(MaterialDialog dialog, View view, int which, CharSequence text) {
sortList(adapter.getCurrencyList(), which);
adapter.notifyDataSetChanged();
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putInt(SORT_SETTING, which);
editor.apply();
favsUpdateCallback.performFavsSort();
Toast toast = Toast.makeText(getContext(), "Sorting by: " + text, Toast.LENGTH_SHORT);
toast.show();
return true;
}
})
.show();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
@Override
public boolean onQueryTextSubmit(String query) {
return false;
}
@Override
public boolean onQueryTextChange(String query) {
currQuery = query;
query = query.toLowerCase();
filteredList.clear();
for (CMCCoin coin : currencyItemList) {
if (coin.getSymbol().toLowerCase().contains(query) || coin.getName().toLowerCase().contains(query)) {
filteredList.add(coin);
}
}
adapter.setCurrencyList(filteredList);
return true;
}
private void showInputMethod(View view) {
InputMethodManager imm = (InputMethodManager) getActivity().getSystemService(Context.INPUT_METHOD_SERVICE);
if (imm != null) {
imm.showSoftInput(view, 0);
}
}
@Override
public void onPrepareOptionsMenu(Menu menu) {
if (searchView != null && searchViewFocused) {
((AppCompatActivity)mContext).getSupportActionBar().setTitle("");
searchView.requestFocusFromTouch();
searchView.setIconified(false);
searchView.setIconified(false);
searchView.setQuery(currQuery, false);
showInputMethod(rootView);
}
}
@Override
public void onCreateOptionsMenu(final Menu menu, MenuInflater inflater) {
getActivity().getMenuInflater().inflate(R.menu.all_currency_list_tab_menu, menu);
searchItem = menu.findItem(R.id.action_search);
searchView = (SearchView) MenuItemCompat.getActionView(searchItem);
searchView.setOnQueryTextListener(this);
// Detect SearchView icon clicks
searchView.setOnSearchClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
searchViewFocused = true;
setItemsVisibility(menu, searchItem, false);
}
});
// Detect SearchView close
searchView.setOnCloseListener(new SearchView.OnCloseListener() {
@Override
public boolean onClose() {
searchViewFocused = false;
setItemsVisibility(menu, searchItem, true);
return false;
}
});
if (searchViewFocused) ((AppCompatActivity)mContext).getSupportActionBar().setTitle("");
super.onCreateOptionsMenu(menu, inflater);
}
private void setItemsVisibility(Menu menu, MenuItem exception, boolean visible) {
for (int i = 0; i < menu.size(); ++i) {
MenuItem item = menu.getItem(i);
if (item != exception) item.setVisible(visible);
}
if (!visible) {
((AppCompatActivity)mContext).getSupportActionBar().setTitle("");
} else {
((AppCompatActivity)mContext).getSupportActionBar().setTitle(getResources().getString(R.string.app_name));
}
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
searchViewFocused = false;
}
public AllCurrencyListAdapter getAdapter() {
return this.adapter;
}
}
我试图四处寻找答案，但是甚至找不到一个，并且由于无法解决，此错误使我感到压力！当我尝试启动此片段时，应用程序崩溃。会提供任何帮助。
答案 0 :(得分：0)
在public void onAttach(Context context)中，传入的上下文似乎是com.steven.test.MainActivity类型，在您看来与com.steven.test.providers.priceticker.currencylist.AllCurrencyListFragment $ FavoritesListUpdate不兼容尝试将其投放到这里：
this.favsUpdateCallback = (FavoritesListUpdater) context;
答案 1 :(得分：0)
我不知道你要做什么。
在您的代码中，您尝试投射
FavoritesListUpdater
到Context
，这就是导致错误的原因。
我认为您想将上下文强制转换为MainActivity吗？
this.favsUpdateCallback = ((MainActivity) getActivity()).favsUpdateCallback ;
你想那样做吗？
答案 2 :(得分：0)
您需要拥有MainActivity ... implements AllCurrencyListFragment.FavoritesListUpdater
该片段将附着到一个活动，因此，at com.steven.test.providers.priceticker.currencylist.AllCurrencyListFragment.onAttach(AllCurrencyListFragment.java:182)（您用来加载此片段的Activity）必须实现该接口。
此外，Fragment不是Context对象的扩展
这是我的活动
您显示了两个片段...