在选项卡之间滑动时，我的android应用仍然崩溃，并出现以下错误:
09-16 16:19:27.142 4750-4750/com.khackett.runmate E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.khackett.runmate, PID: 4750
java.lang.IllegalStateException: Content view not yet created
at android.support.v4.app.ListFragment.ensureList(ListFragment.java:328)
at android.support.v4.app.ListFragment.getListView(ListFragment.java:222)
at com.khackett.runmate.ui.MyRunsFragment$1.done(MyRunsFragment.java:167)
at com.khackett.runmate.ui.MyRunsFragment$1.done(MyRunsFragment.java:135)
at com.parse.ParseTaskUtils$2$1.run(ParseTaskUtils.java:115)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
这是MyRunsFragment:
public class MyRunsFragment extends ListFragment {
protected SwipeRefreshLayout mSwipeRefreshLayout;
// member variable to store the list of routes the user has accepted
protected List<ParseObject> mAcceptedRoutes;
private int MY_STATUS_CODE = 1111;
// Default constructor for MyRunsFragment
public MyRunsFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_my_runs, container, false);
// Set SwipeRefreshLayout component
mSwipeRefreshLayout = (SwipeRefreshLayout) rootView.findViewById(R.id.swipeRefreshLayout);
// Set the onRefreshListener
mSwipeRefreshLayout.setOnRefreshListener(mOnRefreshListener);
mSwipeRefreshLayout.setColorSchemeResources(
R.color.swipeRefresh1,
R.color.swipeRefresh2,
R.color.swipeRefresh3,
R.color.swipeRefresh4);
return rootView;
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
// Retrieve the accepted routes from the Parse backend
retrieveAcceptedRoutes();
}
@Override
public void onResume() {
super.onResume();
}
@Override
public void onListItemClick(ListView l, View v, int position, long id) {
super.onListItemClick(l, v, position, id);
// create the message object which is set to the message at the current position
ParseObject route = mAcceptedRoutes.get(position);
// String messageType = message.getString(ParseConstants.KEY_FILE_TYPE);
JSONArray parseList = route.getJSONArray(ParseConstants.KEY_LATLNG_POINTS);
JSONArray parseListBounds = route.getJSONArray(ParseConstants.KEY_LATLNG_BOUNDARY_POINTS);
String objectId = route.getObjectId();
String routeName = route.getString(ParseConstants.KEY_ROUTE_NAME);
// JSONArray ids = route.getJSONArray(ParseConstants.KEY_RECIPIENT_IDS);
// Start a map activity to display the route
Intent intent = new Intent(getActivity(), MapsActivityTrackRun.class);
intent.putExtra("parseLatLngList", parseList.toString());
intent.putExtra("parseLatLngBoundsList", parseListBounds.toString());
intent.putExtra("myRunsObjectId", objectId);
intent.putExtra("myRunsRouteName", routeName);
// Start the MapsActivityDisplayRoute activity
startActivityForResult(intent, MY_STATUS_CODE);
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
}
private void retrieveAcceptedRoutes() {
// query the routes class/table in parse
// get messages where the logged in user ID is in the list of the recipient ID's (we only want to retrieve the messages sent to us)
// querying the message class is similar to how we have been querying users
ParseQuery<ParseObject> queryRoute = new ParseQuery<ParseObject>(ParseConstants.CLASS_ROUTES);
// use the 'where' clause to search through the messages to find where our user ID is one of the recipients
queryRoute.whereEqualTo(ParseConstants.KEY_ACCEPTED_RECIPIENT_IDS, ParseUser.getCurrentUser().getObjectId());
// order results so that most recent message are at the top of the inbox
queryRoute.addDescendingOrder(ParseConstants.KEY_CREATED_AT);
// query is ready - run it
queryRoute.findInBackground(new FindCallback<ParseObject>() {
// When the retrieval is done from the Parse query, the done() callback method is called
@Override
public void done(List<ParseObject> routes, ParseException e) {
// dismiss the progress indicator here
// getActivity().setProgressBarIndeterminateVisibility(false);
// End refreshing once routes are retrieved
// done() is called from onResume() and the OnRefreshListener
// Need to check that its called from the the OnRefreshListener before ending it
if (mSwipeRefreshLayout.isRefreshing()) {
mSwipeRefreshLayout.setRefreshing(false);
}
// the list being returned is a list of routes
if (e == null) {
// successful - routes found. They are stored as a list in messages
mAcceptedRoutes = routes;
// adapt this data for the list view, showing the senders name
// create an array of strings to store the usernames and set the size equal to that of the list returned
String[] usernames = new String[mAcceptedRoutes.size()];
// enhanced for loop to go through the list of users and create an array of usernames
int i = 0;
for (ParseObject message : mAcceptedRoutes) {
// get the specific key
usernames[i] = message.getString(ParseConstants.KEY_SENDER_NAME);
i++;
}
// Create the adapter once and update its state on each refresh
if (getListView().getAdapter() == null) {
// the above adapter code is now replaced with the following line
RouteMessageAdapter adapter = new RouteMessageAdapter(getListView().getContext(), mAcceptedRoutes);
// Force a refresh of the list once data has changed
adapter.notifyDataSetChanged();
// need to call setListAdapter for this activity. This method is specifically from the ListActivity class
setListAdapter(adapter);
} else {
// refill the adapter
// cast it to RouteMessageAdapter
((RouteMessageAdapter) getListView().getAdapter()).refill(mAcceptedRoutes);
}
}
}
});
}
protected SwipeRefreshLayout.OnRefreshListener mOnRefreshListener = new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
// When list is swiped down to refresh, retrieve the users runs from the Parse backend
retrieveAcceptedRoutes();
}
};
}
还有fragment_my_runs布局文件:
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity$PlaceholderFragment">
<android.support.v4.widget.SwipeRefreshLayout
android:id="@+id/swipeRefreshLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true">
<ListView
android:id="@android:id/list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:clipToPadding="false"
android:paddingBottom="@dimen/inbox_vertical_margin"/>
</android.support.v4.widget.SwipeRefreshLayout>
<TextView
android:id="@android:id/empty"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/empty_inbox_label"
android:textSize="@dimen/default_text_size"/>
</RelativeLayout>
TabFragmentContainer
public class TabFragmentContainer extends Fragment {
// Create the FragmentPagerAdapter that will provide and manage tabs for each section.
public static MyFragmentPagerAdapter myFragmentPagerAdapter;
public static TabLayout tabLayout;
// The ViewPager is a layout widget in which each child view is a separate tab in the layout.
// It will host the section contents.
public static ViewPager viewPager;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
// Inflate tab_layout_fragment_container view and setup views for the TabLayout and ViewPager items.
View view = inflater.inflate(R.layout.tab_layout_fragment_container, null);
tabLayout = (TabLayout) view.findViewById(R.id.tabs);
// Set up the ViewPager with the sections adapter.
viewPager = (ViewPager) view.findViewById(R.id.viewpager);
// Instantiate the adapter that will return a fragment for each of the three sections of the main activity
myFragmentPagerAdapter = new MyFragmentPagerAdapter(getActivity(), getChildFragmentManager());
// Set up the adapter for the ViewPager
viewPager.setAdapter(myFragmentPagerAdapter);
// Runnable() method required to implement setupWithViewPager() method
tabLayout.post(new Runnable() {
@Override
public void run() {
tabLayout.setupWithViewPager(viewPager);
viewPager.setCurrentItem(1, false);
// tabLayout.getTabAt(1).select();
}
});
// Return the created View
return view;
}
}
FragmentPagerAdapter:
public class MyFragmentPagerAdapter extends FragmentPagerAdapter {
// The context to be passed in when the adapter is created.
private Context mContext;
// The number of tabs in the layout.
public static int numberOfTabs = 3;
/**
* Default constructor that accepts a FragmentManager parameter to add or remove fragments.
*
* @param context the context from the activity using the adapter.
* @param fragmentManager the FragmentManager for managing Fragments inside of the TabFragmentContainer.
*/
public MyFragmentPagerAdapter(Context context, FragmentManager fragmentManager) {
super(fragmentManager);
mContext = context;
}
/**
* Method to return the relevant fragment for the selected tab.
*/
@Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return new MyRunsFragment();
case 1:
return new InboxRouteFragment();
case 2:
return new FriendsFragment();
}
return null;
}
/**
* Method that gets the number of tabs in the layout.
*
* @return the number of tabs in the layout.
*/
@Override
public int getCount() {
return numberOfTabs;
}
/**
* Method that returns the title of each tab in the layout.
*/
@Override
public CharSequence getPageTitle(int position) {
Locale locale = Locale.getDefault();
switch (position) {
case 0:
return mContext.getString(R.string.title_section1).toUpperCase(locale);
case 1:
return mContext.getString(R.string.title_section2).toUpperCase(locale);
case 2:
return mContext.getString(R.string.title_section3).toUpperCase(locale);
}
return null;
}
}
包含ViewPager小部件的tab_layout_fragment_container文件:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<android.support.design.widget.TabLayout
android:id="@+id/tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@color/ColorPrimaryPurple"
app:tabGravity="fill"
app:tabIndicatorColor="@color/ColorPrimaryPurple"
app:tabMode="fixed"
app:tabSelectedTextColor="@color/textColorPrimary"
app:tabTextColor="@color/pressedPurpleButton">
</android.support.design.widget.TabLayout>
<android.support.v4.view.ViewPager
android:id="@+id/viewpager"
android:layout_width="match_parent"
android:layout_height="match_parent">
</android.support.v4.view.ViewPager>
</LinearLayout>
我的MainActivity中的
onCreate()方法:@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Initialise the DrawerLayout and NavigationView views.
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawerLayout);
mNavigationView = (NavigationView) findViewById(R.id.navigationDrawerMenu);
// Inflate the first fragment to be displayed when logged into the app.
mFragmentManager = getSupportFragmentManager();
mFragmentTransaction = mFragmentManager.beginTransaction();
mFragmentTransaction.replace(R.id.containerView, new TabFragmentContainer()).commit();
// Setup click events on the NavigationView items.
// When an item is selected, replace the tab fragment container with the requested fragment.
mNavigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(MenuItem menuItem) {
mDrawerLayout.closeDrawers();
if (menuItem.getItemId() == R.id.navItemHome) {
FragmentTransaction tabFragmentContainer = mFragmentManager.beginTransaction();
tabFragmentContainer.replace(R.id.containerView, new TabFragmentContainer()).commit();
}
if (menuItem.getItemId() == R.id.navItemRunHistory) {
FragmentTransaction runHistoryFragment = mFragmentManager.beginTransaction();
runHistoryFragment.replace(R.id.containerView, new RunHistoryFragment()).commit();
}
if (menuItem.getItemId() == R.id.navItemSettings) {
FragmentTransaction settingsFragment = mFragmentManager.beginTransaction();
settingsFragment.replace(R.id.containerView, new SettingsFragment()).commit();
}
if (menuItem.getItemId() == R.id.navItemHelp) {
FragmentTransaction instructionsFragment = mFragmentManager.beginTransaction();
instructionsFragment.replace(R.id.containerView, new InstructionsFragment()).commit();
}
if (menuItem.getItemId() == R.id.navItemMyProfile) {
FragmentTransaction myProfileFragment = mFragmentManager.beginTransaction();
myProfileFragment.replace(R.id.containerView, new MyProfileFragment()).commit();
}
if (menuItem.getItemId() == R.id.navItemLogOut) {
// User has selected log out option. Log user out and return to login screen.
ParseUser.logOut();
navigateToLogin();
}
return false;
}
});
// Set up the Toolbar.
setupToolbar();
}
我在这里遵循了其他答案，并在
getListView()方法中添加了onViewCreated()功能，但问题仍然存在...谁能指出我可能会出问题的地方？ 最佳答案
基于这些事实:
done()调用getListView()时，还没有根 View 。 done()进行的查询得到响应时，将调用retrieveAcceptedRoutes()。 retrieveAcceptedRoutes在多个地方被调用，包括OnRefreshListener mOnRefreshListener，它在之前(即在onCreateView()返回之前)在onCreateView() 中注册为刷新侦听器。 ...有可能在存在根 View 之前调用
getListView()。尝试将这3条语句从
onCreateView()移到onViewCreated()，这样，只有在有根 View 时才可以调用刷新侦听器。 // Set SwipeRefreshLayout component
mSwipeRefreshLayout = (SwipeRefreshLayout) rootView.findViewById(R.id.swipeRefreshLayout);
// Set the onRefreshListener
mSwipeRefreshLayout.setOnRefreshListener(mOnRefreshListener);
mSwipeRefreshLayout.setColorSchemeResources(
R.color.swipeRefresh1,
R.color.swipeRefresh2,
R.color.swipeRefresh3,
R.color.swipeRefresh4);