我尝试在ViewPager中使用ListView，但无法创建适配器。它基本上崩溃了。我有以下代码（由eclipse的模板制成）：
public class WeeklyActivity extends FragmentActivity {
/**
* The {@link android.support.v4.view.PagerAdapter} that will provide
* fragments for each of the sections. We use a
* {@link android.support.v4.app.FragmentPagerAdapter} derivative, which
* will keep every loaded fragment in memory. If this becomes too memory
* intensive, it may be best to switch to a
* {@link android.support.v4.app.FragmentStatePagerAdapter}.
*/
SectionsPagerAdapter mSectionsPagerAdapter;
/**
* The {@link ViewPager} that will host the section contents.
*/
ViewPager mViewPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_weekly);
// Create the adapter that will return a fragment for each of the three
// primary sections of the app.
mSectionsPagerAdapter = new SectionsPagerAdapter(
getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.pager);
mViewPager.setAdapter(mSectionsPagerAdapter);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.weekly, menu);
return true;
}
/**
* A {@link FragmentPagerAdapter} that returns a fragment corresponding to
* one of the sections/tabs/pages.
*/
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a DummySectionFragment (defined as a static inner class
// below) with the page number as its lone argument.
Fragment fragment = new DummySectionFragment();
Bundle args = new Bundle();
args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, position + 1);
fragment.setArguments(args);
return fragment;
}
@Override
public int getCount() {
// Show 3 total pages.
return 5;
}
@Override
public CharSequence getPageTitle(int position) {
Locale l = Locale.getDefault();
switch (position) {
case 0:
return "p1";
case 1:
return "p2";
case 2:
return "p3";
case 3:
return "p4";
case 4:
return "p5";
}
return null;
}
}
/**
* A dummy fragment representing a section of the app, but that simply
* displays dummy text.
*/
public static class DummySectionFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
public static final String ARG_SECTION_NUMBER = "section_number";
public DummySectionFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = (RelativeLayout) inflater.inflate(R.layout.fragment_weekly_dummy, container, false);
ListView lv = (ListView) rootView.findViewById(R.id.time_tv);
String[] lessons = new String[] {"a", "a"};
ArrayAdapter<String> listAdapter = new ArrayAdapter<String>(rootView.getContext(), android.R.layout.simple_list_item_1, lessons);
lv.setAdapter(listAdapter);
return rootView;
}
}
}
fragment_weekly_dummy：
<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"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".WeeklyActivity$DummySectionFragment" >
<ListView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@android:color/white"
android:id="@+id/weekly_list"
android:padding="20dp" />
</RelativeLayout>
LogCat：
12-10 14:28:58.275: D/AndroidRuntime(20794): Shutting down VM
12-10 14:28:58.275: W/dalvikvm(20794): threadid=1: thread exiting with uncaught exception (group=0x41aa6700)
12-10 14:28:58.283: E/AndroidRuntime(20794): FATAL EXCEPTION: main
12-10 14:28:58.283: E/AndroidRuntime(20794): java.lang.NullPointerException
12-10 14:28:58.283: E/AndroidRuntime(20794): at com.dcapps.lessons.WeeklyActivity$DummySectionFragment.onCreateView(WeeklyActivity.java:137)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.support.v4.app.Fragment.performCreateView(Fragment.java:1478)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:927)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1460)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:472)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.support.v4.view.ViewPager.populate(ViewPager.java:1068)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.support.v4.view.ViewPager.populate(ViewPager.java:914)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1436)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.view.View.measure(View.java:15848)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5008)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.view.View.measure(View.java:15848)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5008)
12-10 14:28:58.283: E/AndroidRuntime(20794): at com.android.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:302)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.view.View.measure(View.java:15848)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5008)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
12-10 14:28:58.283: E/AndroidRuntime(20794): at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2189)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.view.View.measure(View.java:15848)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1905)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1104)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1284)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1004)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5481)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.view.Choreographer.doCallbacks(Choreographer.java:562)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.view.Choreographer.doFrame(Choreographer.java:532)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.os.Handler.handleCallback(Handler.java:730)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.os.Handler.dispatchMessage(Handler.java:92)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.os.Looper.loop(Looper.java:137)
12-10 14:28:58.283: E/AndroidRuntime(20794): at android.app.ActivityThread.main(ActivityThread.java:5103)
12-10 14:28:58.283: E/AndroidRuntime(20794): at java.lang.reflect.Method.invokeNative(Native Method)
12-10 14:28:58.283: E/AndroidRuntime(20794): at java.lang.reflect.Method.invoke(Method.java:525)
12-10 14:28:58.283: E/AndroidRuntime(20794): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
12-10 14:28:58.283: E/AndroidRuntime(20794): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
12-10 14:28:58.283: E/AndroidRuntime(20794): at dalvik.system.NativeStart.main(Native Method)
最佳答案
使用getActivity()
ArrayAdapter<String> listAdapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, lessons);
public final Activity getActivity ()Return the Activity this fragment is currently associated with.
编辑
你有这个
<ListView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@android:color/white"
android:id="@+id/weekly_list" // id is weekly_list
android:padding="20dp" />
还有这个
ListView lv = (ListView) rootView.findViewById(R.id.time_tv); // id is not weekly_list
ID确实符合
应该
ListView lv = (ListView) rootView.findViewById(R.id.weekly_list);
还要确保将活动上下文用于arrayadapter。