com.handmark.pulltorefresh.extras.listfragment.PullToRefreshListFragment 抛出 nullpointerException

Question

我收到以下错误：

02-16 12:58:42.444: W/System.err(28893):    at com.railyatri.in.fragments.SelectionFragmentNew.init(SelectionFragmentNew.java:206)
02-16 12:58:42.444: W/System.err(28893):    at com.railyatri.in.fragments.SelectionFragmentNew.onResume(SelectionFragmentNew.java:229)
02-16 12:58:42.444: W/System.err(28893):    at android.support.v4.app.Fragment.performResume(Fragment.java:1829)
02-16 12:58:42.444: W/System.err(28893):    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:983)
02-16 12:58:42.444: W/System.err(28893):    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1126)
02-16 12:58:42.444: W/System.err(28893):    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1108)
02-16 12:58:42.444: W/System.err(28893):    at android.support.v4.app.FragmentManagerImpl.dispatchResume(FragmentManager.java:1927)
02-16 12:58:42.444: W/System.err(28893):    at android.support.v4.app.FragmentActivity.onResumeFragments(FragmentActivity.java:444)
02-16 12:58:42.444: W/System.err(28893):    at android.support.v4.app.FragmentActivity.onPostResume(FragmentActivity.java:433)
02-16 12:58:42.444: W/System.err(28893):    at android.support.v7.app.ActionBarActivity.onPostResume(ActionBarActivity.java:140)
02-16 12:58:42.454: W/System.err(28893):    at android.app.Activity.performResume(Activity.java:5275)
02-16 12:58:42.454: W/System.err(28893):    at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2643)
02-16 12:58:42.454: W/System.err(28893):    at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2681)
02-16 12:58:42.454: W/System.err(28893):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2151)
02-16 12:58:42.454: W/System.err(28893):    at android.app.ActivityThread.access0(ActivityThread.java:140)
02-16 12:58:42.454: W/System.err(28893):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1238)
02-16 12:58:42.454: W/System.err(28893):    at android.os.Handler.dispatchMessage(Handler.java:99)
02-16 12:58:42.454: W/System.err(28893):    at android.os.Looper.loop(Looper.java:137)
02-16 12:58:42.454: W/System.err(28893):    at android.app.ActivityThread.main(ActivityThread.java:4944)
02-16 12:58:42.454: W/System.err(28893):    at java.lang.reflect.Method.invokeNative(Native Method)
02-16 12:58:42.454: W/System.err(28893):    at java.lang.reflect.Method.invoke(Method.java:511)
02-16 12:58:42.464: W/System.err(28893):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038)

我正在使用 android-support-v7-appcompat 开发应用程序。我有以下方法 return null

mPullRefreshListFragment = (PullToRefreshListFragment) ((ActionBarActivity) context)
                    .getSupportFragmentManager().findFragmentById(
                            R.id.frag_ptr_list);

我有以下布局：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/background_img"
android:orientation="vertical" >

<fragment
    android:id="@+id/frag_ptr_list"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    class="com.handmark.pulltorefresh.extras.listfragment.PullToRefreshListFragment"
    />

请帮帮我提前致谢...

Answer 1

如果PullToRefreshListFragment的主机是Activity，那么应该是：

mPullRefreshListFragment = (PullToRefreshListFragment)getActivity()
                .getSupportFragmentManager().findFragmentById(
                        R.id.frag_ptr_list);

但是如果PullToRefreshListFragment的宿主是Fragment，调用方法应该是：

mPullRefreshListFragment = (PullToRefreshListFragment)getChildFragmentManager().findFragmentById(
                        R.id.frag_ptr_list);

com.handmark.pulltorefresh.extras.listfragment.PullToRefreshListFragment 抛出 nullpointerException

com.handmark.pulltorefresh.extras.listfragment.PullToRefreshListFragment throw nullpointerException

android

pull-to-refresh