从片段替换片段时，onRequestPermissionsResult 回调不起作用

Posted 2023-02-19

【中文标题】从片段替换片段时，onRequestPermissionsResult 回调不起作用

【英文标题】：onRequestPermissionsResult callback not working when replacing fragment from a fragment

【发布时间】：2018-01-20 18:58:15

【问题描述】：

我有一个具有 onRequestPermissionsResult 的活动，每当我在运行时请求权限时都会调用它，但是当我从另一个片段替换片段时它不会被调用。

过程是： 我有 3 个片段 片段 A、B 和 C。 片段 A 是附加到 MainActivity 的默认片段，单击按钮时，我将片段 A 替换为片段 B，当我请求片段 B 的权限时，它运行正常，但将片段 B 替换为片段 C 请求权限后抛出异常 fragment未附加到活动

MainActivity 代码：

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) 
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    List<Fragment> fragments = getSupportFragmentManager().getFragments();
    if (fragments != null) 
        for (Fragment fragment : fragments) 

                fragment.onRequestPermissionsResult(requestCode, permissions, grantResults);
        
    

片段 B 代码

Fragment fragment = new ShedDetailFragment();
        Bundle args=new Bundle();
        args.putString("flockno",flockno);
        args.putString("shedno",shedno.get(position));
        fragment.setArguments(args);
        // Insert the fragment by replacing any existing fragment
        FragmentManager fragmentManager = getFragmentManager();
        fragmentManager.beginTransaction()
                .add(fragment,"ShedDetailsFrament")
                .replace(R.id.frame_container, fragment)
                .commit();

C 代码片段

@Override
public void onRequestPermissionsResult(int requestCode,
                                       String permissions[], int[] grantResults) 
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);

    switch (requestCode) 
        case 12:
            // If request is cancelled, the result arrays are empty.
            if (grantResults.length > 0
                    && grantResults[0] == PackageManager.PERMISSION_GRANTED) 

                // permission was granted, yay! Do the
                // contacts-related task you need to do.
                takePhotoFromCamera();
                //Toast.makeText(getActivity(),"Permission Granted for Camera.Please Select Farm Photo",Toast.LENGTH_SHORT).show();

             else 

                // permission denied, boo! Disable the
                // functionality that depends on this permission.
            
            return;
        
        case 11:
            // If request is cancelled, the result arrays are empty.
            if (grantResults.length > 0
                    && grantResults[0] == PackageManager.PERMISSION_GRANTED) 

                // permission was granted, yay! Do the
                // contacts-related task you need to do.
                saveImage(bitmap);
                //Toast.makeText(getActivity(),"Permission Granted for Storage.Please Select Farm Photo",Toast.LENGTH_SHORT).show();

             else 

                // permission denied, boo! Disable the
                // functionality that depends on this permission.
            
            return;
        
        // other 'case' lines to check for other
        // permissions this app might request
    

我允许任何权限时的错误日志

E/androidRuntime: FATAL EXCEPTION: main
              Process: com.artevet.artevet, PID: 32741
              java.lang.RuntimeException: Failure delivering result ResultInfowho=@android:requestPermissions:, request=12, result=-1, data=Intent  act=android.content.pm.action.REQUEST_PERMISSIONS (has extras)  to activity com.artevet.artevet/com.artevet.artevet.MainActivity: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v4.app.Fragment.onRequestPermissionsResult(int, java.lang.String[], int[])' on a null object reference
                  at android.app.ActivityThread.deliverResults(ActivityThread.java:4998)
                  at android.app.ActivityThread.handleSendResult(ActivityThread.java:5041)
                  at android.app.ActivityThread.access$1600(ActivityThread.java:229)
                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1875)
                  at android.os.Handler.dispatchMessage(Handler.java:102)
                  at android.os.Looper.loop(Looper.java:148)
                  at android.app.ActivityThread.main(ActivityThread.java:7325)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
               Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v4.app.Fragment.onRequestPermissionsResult(int, java.lang.String[], int[])' on a null object reference
                  at com.artevet.artevet.MainActivity.onRequestPermissionsResult(MainActivity.java:383)
                  at android.app.Activity.dispatchRequestPermissionsResult(Activity.java:7291)
                  at android.app.Activity.dispatchActivityResult(Activity.java:7169)
                  at android.app.ActivityThread.deliverResults(ActivityThread.java:4994)
                  at android.app.ActivityThread.handleSendResult(ActivityThread.java:5041) 
                  at android.app.ActivityThread.access$1600(ActivityThread.java:229) 
                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1875) 
                  at android.os.Handler.dispatchMessage(Handler.java:102) 
                  at android.os.Looper.loop(Looper.java:148) 
                  at android.app.ActivityThread.main(ActivityThread.java:7325) 
                  at java.lang.reflect.Method.invoke(Native Method) 
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230) 
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120) 

【参考方案1】：

您是否有任何具体原因向您的活动请求权限？您可以只处理每个片段中的权限。因为片段有自己的requestPermissions() 和onRequestPermissionsResult 方法。例如见this

【讨论】：

非常感谢你让我开心，再次感谢我学会了在片段中请求运行时权限的新方法

很高兴为您提供帮助。干杯