在fragment中重写onActivityResult时出现空指针异常NullPointerException_fragment 里面重写 onactivityresult-优快云博客

本文详细介绍了在Android应用中，如何在Fragment中正确处理从相机返回的图片，避免了因错误地调用onActivityResult方法而导致的空指针异常。通过检查findFragmentById返回的Fragment是否为空，确保了代码的稳定性和可靠性。

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因为要在fragment中获取相机返回的图片，因此重写了一下onActivityResult这个方法

@Override
    public void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == CAMERA_REQUEST_CODE){
            if (resultCode == RESULT_OK){
                Toast.makeText(getActivity().getApplicationContext(),
                        "get picture,path = "+mFilePath,Toast.LENGTH_SHORT).show();
                displayImage(mFilePath);
            }else if (resultCode == RESULT_CANCELED){
                
            }else{
                
            }
        }else if(requestCode == ALBUM_REQUEST_CODE){
            if(resultCode == RESULT_OK){
                if(Build.VERSION.SDK_INT >= 19){
                    handleImageOnKitKat(data);
                }else{
                    handleImageBeforeKitKat(data);
                }
            }
        }
    }

然后在Activity中也重写了onActivityResult这个方法

@Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        Fragment f = this.getSupportFragmentManager().findFragmentById(0);
        f.onActivityResult(requestCode,resultCode,data);
    }

结果在调用相机后按返回键会出现空指针异常

解决方案：

对findFragmentById返回的Fragment进行判空操作，就解决了。


    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data){
        super.onActivityResult(requestCode, resultCode, data);
        Fragment f = this.getSupportFragmentManager().findFragmentById(0);
        if (f != null) {
            f.onActivityResult(requestCode,resultCode,data);
        }
    }