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

小灰灰 2022-05-06 11:30 303阅读 1赞

Fragment null must be a public static class to be properly recreated from instance state.  
Android里做一个RadioGroup实现底部导航页面，遇到了这样的问题：

FATAL EXCEPTION: main
    java.lang.IllegalStateException: Fragment null 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.replace(BackStackRecord.java:481)
    at android.support.v4.app.BackStackRecord.replace(BackStackRecord.java:472)
    at com.example.wu.mobileplayer.Activity.Activity.MainActivity.setFragment(MainActivity.java:72)
    at com.example.wu.mobileplayer.Activity.Activity.MainActivity.onCheckedChanged(MainActivity.java:65)
    at android.widget.RadioGroup.setCheckedId(RadioGroup.java:174)
    at android.widget.RadioGroup.access$600(RadioGroup.java:54)
    at android.widget.RadioGroup$CheckedStateTracker.onCheckedChanged(RadioGroup.java:358)
    at android.widget.CompoundButton.setChecked(CompoundButton.java:139)
    at android.widget.CompoundButton.toggle(CompoundButton.java:91)
    at android.widget.RadioButton.toggle(RadioButton.java:76)
    at android.widget.CompoundButton.performClick(CompoundButton.java:103)
    at android.view.View$PerformClick.run(View.java:18803)
    at android.os.Handler.handleCallback(Handler.java:730)
    at android.os.Handler.dispatchMessage(Handler.java:92)
    at android.os.Looper.loop(Looper.java:137)
    at android.app.ActivityThread.main(ActivityThread.java:5493)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:525)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1209)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1025)
    at dalvik.system.NativeStart.main(Native Method)

## 代码的一部分: ##

public class MainActivity extends FragmentActivity implements RadioGroup.OnCheckedChangeListener{ 
    private RadioGroup radioGroup;
    private ArrayList basePagers;
    private int position;
    @Override
    protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    radioGroup = (RadioGroup) findViewById(R.id.rg_selector);
    radioGroup.check(R.id.rb_video);
    
        basePagers = new ArrayList<>();
        basePagers.add(new VideoPager(this));
        basePagers.add(new AudioPager(this));
        basePagers.add(new NetVideoPager(this));
        basePagers.add(new NetAudioPager(this));
        //设置监听
        radioGroup.setOnCheckedChangeListener(this);
    
        }
    
    
    
        @Override
        public void onCheckedChanged(RadioGroup group, int checkedId) { 
            switch (checkedId) { 
                case R.id.rb_video:
                    position = 0;
                    break;
                case R.id.rb_audio:
                    position=1;
                    break;
                case R.id.rb_net_video:
                    position=2;
                    break;
                case R.id.rb_net_audio:
                    position=3;
                    break;
            }
            setFragment();
        }
    
    
    private void setFragment() { 
       FragmentManager manager = getSupportFragmentManager();
        FragmentTransaction ft = manager.beginTransaction();
        ft.replace(R.id.fl_content,new Fragment(){ 
            @Nullable
            @Override
            public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) { 
               BasePager basePager = getBasePager();
                if(basePager!=null) { 
                    return basePager.rootView;
                }
                return null;
    
            }
        });
        ft.commit();
    }
    
    private BasePager getBasePager() { 
        BasePager basePager = basePagers.get(position);
        if(basePager!=null && !basePager.isinitData) { 
            basePager.isinitData = true;
            basePager.initData();
        }
        return basePager;
    }

\#\#\#解决办法  
把new Fragment那段代码拿出来，单独创建一个Fragment，然后使用时直接new出来就可以了。  
原new Fragmen代码修改为：

`ft.replace(R.id.fl_main_content,new ReplaceFragment(getBasePager()));`

然后创建ReplaceFragment类，代码发如下：

public class ReplaceFragment extends Fragment { 
    
    private BasePager currPager;
    
    public ReplaceFragment(BasePager pager) { 
        this.currPager=pager;
    }
    
    
    @Override
    public void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState);
    }
    
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) { 
        return currPager.rootView;
    	}
    }