Question

调用notifyDataSetChange时，ViewPager会抛出NullPointerException。

我认为这是支持库中的一个错误，因为我的适配器不为空

堆栈追踪：

06-30 20:16:13.160 1578-1578/com.umeugwaDabeluchi.Ume E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.umeugwaDabeluchi.Ume, PID: 1578
java.lang.NullPointerException
    at android.support.v4.app.FragmentManagerImpl.execSingleAction(FragmentManager.java:1623)
    at android.support.v4.app.BackStackRecord.commitNowAllowingStateLoss(BackStackRecord.java:637)
    at android.support.v4.app.FragmentStatePagerAdapter.finishUpdate(FragmentStatePagerAdapter.java:166)
    at android.support.v4.view.ViewPager.populate(ViewPager.java:1235)
    at android.support.v4.view.ViewPager.setCurrentItemInternal(ViewPager.java:666)
    at android.support.v4.view.ViewPager.setCurrentItemInternal(ViewPager.java:628)
    at android.support.v4.view.ViewPager.dataSetChanged(ViewPager.java:1077)
    at android.support.v4.view.ViewPager$PagerObserver.onChanged(ViewPager.java:3060)
    at android.support.v4.view.PagerAdapter.notifyDataSetChanged(PagerAdapter.java:284)
    at com.umeugwaDabeluchi.Ume.Fragments.EditFile.OnFileReady(EditFile.java:62)
    at com.umeugwaDabeluchi.Ume.Utility.DataManager$2.run(DataManager.java:204)
    at android.os.Handler.handleCallback(Handler.java:733)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:146)
    at android.app.ActivityThread.main(ActivityThread.java:5635)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:515)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107)
    at dalvik.system.NativeStart.main(Native Method)

Answer 1

@Override
public void OnFileReady() {
    adapter.notifyDataSetChanged();//throws nullPointer Exception
    Log.i(TAG, "EditFile OnFileReady: ");
}

@Override
public void OnDataRemoved(int pos) {
    adapter.notifyDataSetChanged();//throws nullPointer Exception
    Log.i(TAG, "OnDataRemoved: " + "Page removed");
}

Answer 2

开启你的开发者选项中不要保留活动吗？如果为true，请参阅此https://testsmirk.com/2016/10/14/android-viewpager-bug/

调用notifyDataSetChange时，ViewPager抛出NullPointerException

2 个答案: