我正在制作新闻应用程序，我在内部片段中有Gridview，并且在配置更改时我实现了onSaveInstanceState和onRestoreInstanceState .
低于我得到的错误
致命异常：主程序：com.edgar.yodgorbekkomilo.newsapp，PID：5676 java.lang.NullPointerException：尝试在空对象引用上调用虚方法'android.os.Parcelable android.widget.GridView.onSaveInstanceState（）' com.edgar.yodgorbekkomilo.newsapp.AllNewsFragmentTab.onCreateView（AllNewsFragmentTab.java:53）在android.support.v4.app.Fragment.performCreateView（Fragment.java:2354）的android.support.v4.app.FragmentManagerImpl.moveToState（ FragmentManager.java:1419）在Android.support.v4上有android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState（FragmentManager.java:1740），位于android.support.v4上的android.support.v4.app.FragmentManagerImpl.moveToState（FragmentManager.java:1809） .app.BackStackRecord.executeOps（BackStackRecord.java:799）在android.support.v4.app.FragmentManagerImpl.executeOps（FragmentManager.java:2580）android.support.v4.app.FragmentManagerImpl.executeOpsTogether（FragmentManager.java:2367） ）在android.support.v4.app.FragmentManagerImpl.removeRedundantOpera在Android.support的android.support.v4.app.BackStackRecord.commitNowAllowingStateLoss（BackStackRecord.java:651）的android.support.v4.app.FragmentManagerImpl.execSingleAction（FragmentManager.java:2199）上的tionsAndExecute（FragmentManager.java:2322） .v4.app.FragmentStatePagerAdapter.finishUpdate（FragmentStatePagerAdapter.java:167）位于android.support.v4.view.ViewPager.populate（ViewPager.java:1236）的android.support.v4.view.ViewPager.populate（ViewPager.java） ：1084）在android.view.measure.View.measure（View.java:22002）的android.sview.View.measure（View.java： . 6580）在android.sview.View.measure的android.support.design.widget.CoordinatorLayout.onMeasureChild（CoordinatorLayout.java:714）android.support.design.widget.CoordinatorLayout.onMeasure（CoordinatorLayout.java:786） .java：22002）在Android.widget.FrameLayout.onMeasure（FrameLayout . ）的android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:6580） . java：185）在android.view.measure.View.measure（View.java:22002）上的android.sview.vs.Widget.ContentChildMaygins（View.java:2200）上的android.support.v7.widget.ContentFrameLayout.onMeasure（ContentFrameLayout.java:139）（ViewGroup.java） ：6580）android.widget.LinearLayout.measureChildBeforeLayout.Rayout . 在Android.widget.Linear.measureVertical（LinearLayout.java：806）的android.widget.LinearLayout.onMeasure（LinearLayout.java:685） .view.View.measure（View.java:22002）位于android.view.View上的android.view.measureGroup.measureChildMaygins（ViewGroup.java:6580）android.widget.FrameLayout.onMeasure（FrameLayout.java:185） . 在Android.widget.Lineout.measureVertical（LinearLayout.java）的android.widget.LinearLayout.measureChildBeforeLayout（LinearLayout.java:1514）上的android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:6580）测量（View.java:22002） ：806）在android.view上的android.view.View.measure（View.java:22002）的android.widget.LinearLayout.onMeasure（LinearLayout.java:685） . 在android.view.View的com.android.internal.policy.DecorView.onMeasure（DecorView.java:721）的android.widget.FrameLayout.onMeasure（FrameLayout.java:185）上的ViewGroup.measureChildWithMargins（ViewGroup.java:6580） .measure（View.java:22002）在android.view.ViewRootImpl.performMeasure（ViewRootImpl.java:2410）的android.view.ViewRootImpl.measureHierarchy（ViewRootImpl.java:1498）android.view.ViewRootImpl.performTraversals（ViewRootImpl . java：1751）在android.view.ViewRootImpl上的android.view.ViewRootImpl.doTraversal（ViewRootImpl.java:1386）在Android.view.Choreographer $ TraversRecord.run（Choreographer.java ：911）在Android.view.Choreographer（Page 4）上的android.view.Chocographer.doCallbacks（Choreographer.java：723），android.view.Choreographer $ FrameDisplayEventReceiver.run（Choreographer.java:897）在android.os.Handler.handleCallback（Handler.java:789)03-17 20：12：26.358 5676-5676 / com.edgar.yodgorbekkomilo.newsapp E / AndroidRunti我：在android.o.Handler.dispatchMessage（Handler.java:98）的android.app.Looper.loop（Looper.java:164）在android.app.ActivityThread.main（ActivityThread.java:6541）的java . lang.reflect.Method.invoke（Native Method）atcom.android.internal.os.Zygote $ MethodAndArgsCaller.run（Zygote.java:240）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:767）和我的Fragment下面，我实现了配置更改
公共类AllNewsFragmentTab扩展Fragment {
public ArrayList<News> articleList;
ArrayList<Article> articleArrayList = new ArrayList<>();
public GridView gridView;
private View parentView;
private ArticleAdapter adapter;
Parcelable state;
// ...
//恢复索引和位置
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.all_news_fragment_tab, container, false);
gridView = view.findViewById(R.id.listView);
articleList = new ArrayList<>();
parentView = view.findViewById(R.id.parentLayout);
state = gridView.onSaveInstanceState();
/**
* Getting List and Setting List Adapter
*
*
*/
gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// Snackbar.make（parentView，articleArrayList.get（position）.getStatus（）“=>”articleArrayList.get（position）.getTotalResults（），Snackbar.LENGTH_LONG） . show（）; Intent i = new Intent（getContext（），NewsDetailActivity.class）;
i.putExtra("myDataKey", articleArrayList.get(position));
startActivity(i);
}
});
Toast toast = Toast.makeText(getActivity().getApplicationContext(), R.string.string_click_to_load, Toast.LENGTH_LONG);
toast.setGravity(Gravity.CENTER, 0, 0);
toast.show();
/**
* Checking Internet Connection
*/
if (InternetConnection.checkConnection(getActivity().getApplicationContext())) {
final ProgressDialog dialog;
/**
* Progress Dialog for User Interaction
*/
dialog = new ProgressDialog(getActivity());
dialog.setTitle(getString(R.string.string_getting_json_title));
dialog.setMessage(getString(R.string.string_getting_json_message));
dialog.dismiss();
//Creating an object of our api interface
ApiService api = RetroClient.getApiService();
/**
* Calling JSON
*/
Call<News> call = api.getAllNews();
/**
* Enqueue Callback will be call when get response...
*/
call.enqueue(new Callback<News>() {
@Override
public void onResponse(Call<News> call, Response<News> response) {
//Dismiss Dialog
dialog.dismiss();
if (response.isSuccessful()) {
/**
* Got Successfully
*/
// String articleList = String.valueOf(response.body());
News news = response.body();
articleArrayList.addAll(news.getArticles());
/**
* Binding that List to Adapter
*/adapter = new ArticleAdapter(getActivity(), articleArrayList);
gridView.setAdapter(adapter);
if(state != null) {
gridView.onRestoreInstanceState(state);
}
} else {
Snackbar.make(parentView, R.string.string_some_thing_wrong, Snackbar.LENGTH_LONG).show();
}
}
@Override
public void onFailure(Call<News> call, Throwable t) {
dialog.dismiss();
}
});
} else {
Snackbar.make(parentView, R.string.string_internet_connection_not_available, Snackbar.LENGTH_LONG).show();
}
return view;
}
}
below my all_news_fragment_tab.xml where I have declared my fragment
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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="match_parent"
android:orientation="vertical">
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:textAppearance="?android:attr/textAppearanceLarge" />
<GridView
android:id="@+id/listView"
android:layout_width="fill_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior" />
</RelativeLayout>