Question

我正在创建新闻应用程序，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

致命的例外：主要过程：com.edgar.yodgorbekkomilo.newsapp，PID：5676 java.lang.NullPointerException：尝试调用虚方法＆＃39; android.os.Parcelable android.widget.GridView.onSaveInstanceState（）＆＃39;在null对象引用上在com.edgar.yodgorbekkomilo.newsapp.AllNewsFragmentTab.onCreateView（AllNewsFragmentTab.java:53）在android.support.v4.app.Fragment.performCreateView（Fragment.java:2354）在android.support.v4.app.FragmentManagerImpl.moveToState（FragmentManager.java:1419）在android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState（FragmentManager.java:1740）在android.support.v4.app.FragmentManagerImpl.moveToState（FragmentManager.java:1809）在android.support.v4.app.BackStackRecord.executeOps（BackStackRecord.java:799）在android.support.v4.app.FragmentManagerImpl.executeOps（FragmentManager.java:2580）在android.support.v4.app.FragmentManagerImpl.executeOpsTogether（FragmentManager.java:2367）在android.support.v4.app.FragmentManagerImpl.removeRedundantOperationsAndExecute（FragmentManager.java:2322）在android.support.v4.app.FragmentManagerImpl.execSingleAction（FragmentManager.java:2199）在android.support.v4.app.BackStackRecord.commitNowAllowingStateLoss（BackStackRecord.java:651）在android.support.v4.app.FragmentStatePagerAdapter.finishUpdate（FragmentStatePagerAdapter.java:167）在android.support.v4.view.ViewPager.populate（ViewPager.java:1236）在android.support.v4.view.ViewPager.populate（ViewPager.java:1084）在android.support.v4.view.ViewPager.onMeasure（ViewPager.java:1614）在android.view.View.measure（View.java:22002）在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:6580）在android.support.design.widget.CoordinatorLayout.onMeasureChild（CoordinatorLayout.java:714）在android.support.design.widget.CoordinatorLayout.onMeasure（CoordinatorLayout.java:786）在android.view.View.measure（View.java:22002）在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:6580）在android.widget.FrameLayout.onMeasure（FrameLayout.java:185）在android.support.v7.widget.ContentFrameLayout.onMeasure（ContentFrameLayout.java:139）在android.view.View.measure（View.java:22002）在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:6580）在android.widget.LinearLayout.measureChildBeforeLayout（LinearLayout.java:1514）在android.widget.LinearLayout.measureVertical（LinearLayout.java:806）在android.widget.LinearLayout.onMeasure（LinearLayout.java:685）在android.view.View.measure（View.java:22002）在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:6580）在android.widget.FrameLayout.onMeasure（FrameLayout.java:185）在android.view.View.measure（View.java:22002）在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:6580）在android.widget.LinearLayout.measureChildBeforeLayout（LinearLayout.java:1514）在android.widget.LinearLayout.measureVertical（LinearLayout.java:806）在android.widget.LinearLayout.onMeasure（LinearLayout.java:685）在android.view.View.measure（View.java:22002）在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:6580）在android.widget.FrameLayout.onMeasure（FrameLayout.java:185）在com.android.internal.policy.DecorView.onMeasure（DecorView.java:721）在android.view.View.measure（View.java:22002）在android.view.ViewRootImpl.performMeasure（ViewRootImpl.java:2410）在android.view.ViewRootImpl.measureHierarchy（ViewRootImpl.java:1498）在android.view.ViewRootImpl.performTraversals（ViewRootImpl.java:1751）在android.view.ViewRootImpl.doTraversal（ViewRootImpl.java:1386）在android.view.ViewRootImpl $ TraversalRunnable.run（ViewRootImpl.java:6733）在android.view.Choreographer $ CallbackRecord.run（Choreographer.java:911）在android.view.Choreographer.doCallbacks（Choreographer.java:723）在android.view.Choreographer.doFrame（Choreographer.java:658）在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 / AndroidRuntime：at android.os.Handler.dispatchMessage（Handler.java:98）在android.os.Looper.loop（Looper.java:164）在android.app.ActivityThread.main（ActivityThread.java:6541） at java.lang.reflect.Method.invoke（Native Method）在com.android.internal.os.Zygote $ MethodAndArgsCaller.run（Zygote.java:240）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:767）在我的Fragment下面，我实现了配置更改

公共类AllNewsFragmentTab扩展了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（）+＆＃34; =＆gt;＆＃34; + articleArrayList.get（position）.getTotalResults（），Snackbar.LENGTH_LONG）。节目（）; 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>

android.os.Parcelable android.widget.GridView.onSaveInstanceState（）＆＃39;在null？

0 个答案: