Question

我有一个DialogFragment，显示用户是否尝试执行之前已拒绝其权限的操作。

DialogFragment代码编译正常，但由于理由它不会在Dialog中显示消息，除非手机转为横向，之后消息仍然存在。

] 3

这是我的Dialog Fragment代码：

public class PermissionDialog extends DialogFragment {

    private String title;
    private String reason;
    PermissionListener pListener;

    public PermissionDialog() {
        // Required empty public constructor

    }

    public interface PermissionListener{
        //Interface listener so that activities which have dialogs can hear outcomes of events
        void onDialogPositiveClick(DialogFragment dFragment);
        void onDialogNegativeClick(DialogFragment dFragment);
    }
    @NonNull
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState){
        //Set up the elements in the dialog including listeners
        AlertDialog.Builder permissDialog = new AlertDialog.Builder(getActivity());
        if (savedInstanceState!=null){
            Bundle args = getArguments();
            title = args.getString("title","");
            reason = args.getString("reason","");
        }
        permissDialog.setMessage(reason);
        permissDialog.setTitle(title);
        permissDialog.setPositiveButton(R.string.ok_button, new DialogInterface.OnClickListener(){
            @Override
            public void onClick(DialogInterface dialog, int id) {
                // Send the positive button event back to the host activity
                pListener.onDialogPositiveClick(PermissionDialog.this);
            }
        });
        permissDialog.setNegativeButton(R.string.cancel_button, new DialogInterface.OnClickListener(){
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {
                pListener.onDialogNegativeClick(PermissionDialog.this);
            }
        });
        return permissDialog.create();
    }

    @Override
    public void onAttach(Activity activity){
        //This method will ensure the activity implements the interface for sending events
        super.onAttach(activity);
        try {
            pListener = (PermissionListener) activity;
        }catch(ClassCastException e){
            Toast.makeText(getActivity(), "Error in requesting permissions", Toast.LENGTH_SHORT).show();
        }
    }

}

这是创建片段的方法：

private void checkStoragePermission() {
        //This method will check whether the user has granted the permission to write their picture to external storage
        if (Build.VERSION.SDK_INT<= Build.VERSION_CODES.LOLLIPOP_MR1){
            //Users device runs Lollipop or lower so we do not need to check permissions
            savePicture();
        }else{
            if (ContextCompat.checkSelfPermission(this,
                    Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED){
                //Permission hasn't been granted - we should check if the user has denied this permission before
                if (ActivityCompat.shouldShowRequestPermissionRationale(this,
                        Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
                    //Build a dialog to explain to user why permission is required
                    PermissionDialog storageDialog = new PermissionDialog();
                    Bundle args = new Bundle();
                    args.putString("title", "Approve Permission?");
                    args.putString("reason", "This is required in order to write graph to external storage.");
                    storageDialog.setArguments(args);
                    storageDialog.show(getSupportFragmentManager(),"storage_dialog");
                }else{
                    //Request permission
                    ActivityCompat.requestPermissions(this,
                            new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},WRITE_EXTERNAL_CODE);
                }
            }else if (ContextCompat.checkSelfPermission(this,Manifest.permission.WRITE_EXTERNAL_STORAGE) ==PackageManager.PERMISSION_GRANTED){
                //Permission has been granted, we can save the picture.
                savePicture();
            }
        }
    }

Answer 1

我认为savedInstanceState!=null错了。您打算查看savedInstanceState==null吗？

此外，我认为此检查不是必需的。

像这样：

@NonNull
@Override
public Dialog onCreateDialog(Bundle savedInstanceState){
    ....
    AlertDialog.Builder permissDialog = new AlertDialog.Builder(getActivity());
    Bundle args = getArguments();
    permissDialog.setMessage(args.getString("reason",""));
    permissDialog.setTitle(args.getString("title",""));
    ....
}

首次savedInstanceState来电时，

onCreateDialog为空。旋转设备时，Android操作系统会重新创建DialogFragment。使用onCreateDialog调用savedInstanceState != null。

Here是文档。

<强> savedInstanceState

Bundle：如果非null，则从此处给出的先前保存状态重新构造此片段。

除非手机处于横向状态，否则不会显示DialogFragment

1 个答案: