在android studio中升级repo v9后，片段必须是公共静态类崩溃错误

Posted 2023-04-15

【中文标题】在android studio中升级repo v9后，片段必须是公共静态类崩溃错误

【英文标题】：Fragment must be a public static class crash error after upgrade repo v9 in android studio

【发布时间】：2017-02-12 16:13:08

【问题描述】：

我是 android 的新手。我想创建一个具有 3 个水平页面的活动。每个页面都有一个网格视图。我使用 ViewPager 创建页面并为每个页面使用 GridView。以下是代码

public class CategoryActivity extends ActionBarActivity 

    static final int NUM_ITEMS = 3;

    MyAdapter mAdapter;

    ViewPager mPager;

    @Override
    protected void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        setContentView(R.layout.fragment_pager);

        getSupportActionBar().hide();

        mAdapter = new MyAdapter(this.getSupportFragmentManager());

        mPager = (ViewPager)findViewById(R.id.pager);
        mPager.setAdapter(mAdapter);

    

    //MyAdapter is adapter for Pager
    public class MyAdapter extends FragmentPagerAdapter 

        ArrayList<ArrayListFragment> fragments;
        public MyAdapter(FragmentManager fm) 
            super(fm);

            fragments = new ArrayList<>();

            for (int i = 0; i < NUM_ITEMS; i++) 
                ArrayListFragment f = new ArrayListFragment();

                fragments.add(f);
            
       

        @Override
        public int getCount() 
            return NUM_ITEMS;
        

        @Override
        public Fragment getItem(int position) 

            //For each page -> get fragment for that page
            ArrayListFragment f = fragments.get(position);

            return f;
        
    

    //Adapter for each grid view in each Page
    public class ImageAdapter extends BaseAdapter 
        private Context mContext;
        private View parentView;

        public ImageAdapter(Context c) 
            mContext = c;
        

        public ImageAdapter(Context c, View aParentView) 
            mContext = c;
            parentView = aParentView;
        

        public int getCount() 
            return mThumbIds.length;
        

        public Object getItem(int position) 
            return null;
        

        public long getItemId(int position) 
            return 0;
        

        // create a new ImageView for each item referenced by the Adapter
        public View getView(int position, View convertView, ViewGroup parent)        
            View itemView;
            if (convertView == null) 

                //I really config view for each item in grid view....
                //The problem is not here
                //..........
            
            return itemView;
        

        // references to our images
        private Integer[] mThumbIds = 
                R.drawable.images, R.drawable.images,
                R.drawable.images, R.drawable.images,
                R.drawable.images, R.drawable.images,
                R.drawable.images, R.drawable.images,
                R.drawable.images, R.drawable.images,
                R.drawable.images, R.drawable.images
        ;
    

    public class ArrayListFragment extends Fragment 

        /**
         * When creating, retrieve this instance's number from its arguments.
         */
        @Override
        public void onCreate(Bundle savedInstanceState) 
            super.onCreate(savedInstanceState);
        

        /**
         * The Fragment's UI is just a simple text view showing its
         * instance number.
         */
        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) 
            final View v = inflater.inflate(R.layout.fragment_pager_list, container, false);

            GridView gridview = (GridView) v.findViewById(R.id.categridview);

            ImageAdapter ia = new ImageAdapter(CategoryActivity.this, gridview);
            gridview.setAdapter(ia);

            return v;
        


        @Override
        public void onActivityCreated(Bundle savedInstanceState) 
            super.onActivityCreated(savedInstanceState);

        

    

它在 repo v7 中运行良好。但是在我升级到 repo v9 后，它在启动后崩溃并出现错误

E/AndroidRuntime: FATAL EXCEPTION: main
                  Process: <my project process>, PID: 1901
                  java.lang.IllegalStateException: Fragment <my project package>.CategoryActivity.ArrayListFragment must be a public static class to be  properly recreated from instance state.
                      at android.support.v4.app.BackStackRecord.doAddOp(BackStackRecord.java:435)
                      at android.support.v4.app.BackStackRecord.add(BackStackRecord.java:426)
                      at android.support.v4.app.FragmentPagerAdapter.instantiateItem(FragmentPagerAdapter.java:103)
                      at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:1006)
                      at android.support.v4.view.ViewPager.populate(ViewPager.java:1154)
                      at android.support.v4.view.ViewPager.populate(ViewPager.java:1088)
                      at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1614)
                      at android.view.View.measure(View.java:18788)
                      at android.widget.LinearLayout.measureVertical(LinearLayout.java:901)
                      at android.widget.LinearLayout.onMeasure(LinearLayout.java:630)
                      at android.view.View.measure(View.java:18788)
                      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
                      at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
                      at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135)
                      at android.view.View.measure(View.java:18788)
                      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
                      at android.support.v7.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:389)
                      at android.view.View.measure(View.java:18788)
                      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
                      at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
                      at android.view.View.measure(View.java:18788)
                      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
                      at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1465)
                      at android.widget.LinearLayout.measureVertical(LinearLayout.java:748)
                      at android.widget.LinearLayout.onMeasure(LinearLayout.java:630)
                      at android.view.View.measure(View.java:18788)
                      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
                      at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
                      at com.android.internal.policy.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2643)
                      at android.view.View.measure(View.java:18788)
                      at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2100)
                      at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1216)
                      at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1452)
                      at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1107)
                      at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6013)
                      at android.view.Choreographer$CallbackRecord.run(Choreographer.java:858)
                      at android.view.Choreographer.doCallbacks(Choreographer.java:670)
                      at android.view.Choreographer.doFrame(Choreographer.java:606)
                      at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:844)
                      at android.os.Handler.handleCallback(Handler.java:739)
                      at android.os.Handler.dispatchMessage(Handler.java:95)
                      at android.os.Looper.loop(Looper.java:148)
                      at android.app.ActivityThread.main(ActivityThread.java:5417)
                      at java.lang.reflect.Method.invoke(Native Method)
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
I/Process: Sending signal. PID: 1901 SIG: 9
Application terminated.

我搜索了几天，但找不到任何帮助来解决它 有人在

遇到了类似的问题

Android IllegalStateException: Fragment null must be a public static class to be properly recreated from instance state

和

Fragment must be a public static class to be properly recreated from instance state

为什么 ArrayListFragment 必须是一个公共静态类，我想每个必须有一个单独的片段

这是什么问题，谁能帮我解决一下

【参考方案1】：

ArrayListFragment 是否与 CategoryActivity 在同一个 java 文件中？如果为真，则静态类意味着可以创建 ArrayListFragment 的实例，而无需创建 CategoryActivity 的实例。所以每个类都可以有自己的 ArrayListFragment 实例。

【讨论】：

是的，都在一个 java 文件中。不过我不是很明白，能不能解释的再清楚一点。我该怎么办？顺便说一句，我从另一个活动创建 CategoryActivity 的实例，只需为 CategoryActivity 创建一个 Intent 并启动它，没什么特别的。而CategoryActivity类中的所有代码都如上所示，仅此而已

当然。阅读 Java 中的嵌套类及其实例化规则。您应该为 ArrayListFragment（和其他片段）创建单独的 java 文件，或者将嵌套片段类声明为静态。这里有一些有用的链接：docs.oracle.com/javase/tutorial/java/javaOO/nested.html***.com/questions/15571010/…

感谢 Viktor Dolgalyov，我将 ArrayListFragment 移动到另一个 Java 文件，它可以工作。我应该阅读更多关于它的信息