如果我不选择任何图片，然后单击后退按钮，它坠毁

Question

错误消息：

FATAL EXCEPTION: main 
Process: com.example.keepair.myapplication, PID: 31796 
java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=66536, result=0, data=null} to activity {com.example.keepair.myapplication/com.example.keepair.myapplication.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.net.Uri android.content.Intent.getData()' on a null object reference 

CODE：

mGetImageFromGalleryButton = (Button) view.findViewById(R.id.btn_getgallery); 
    mGetImageFromGalleryButton.setOnClickListener(new View.OnClickListener() { 
       @Override 
       public void onClick(View view) { 
        if(ActivityCompat.checkSelfPermission(getActivity(), 
          Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) 
        { 
         requestPermissions(
           new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, 
           2000); 
        } 
        else { 
         startGallery(); 
        } 
       } 
      }); 

    private void startGallery() { 
     Intent cameraIntent = new Intent(Intent.ACTION_PICK, MediaStore.Images.Media.EXTERNAL_CONTENT_URI); 
     cameraIntent.setType("image/*"); 
     if (cameraIntent.resolveActivity(getActivity().getPackageManager()) != null) { 
      startActivityForResult(cameraIntent, 1000); 
     } 
    } 

    @Override 
    public void onActivityResult(int requestCode, int resultCode, Intent data) { 
     if(resultCode == Activity.RESULT_OK) { 
      if(requestCode == 1000){ 
       Uri returnUri = data.getData(); 
       Bitmap bitmapImage = null; 
       try { 
        bitmapImage = MediaStore.Images.Media.getBitmap(getActivity().getContentResolver(), returnUri); 
       } catch (IOException e) { 
        e.printStackTrace(); 
       } 
       mImageview.setImageBitmap(bitmapImage); 
      } 
      returnUri = data.getData(); 
      Glide.with(this) 
       .load(returnUri) 
       .override(1280, 1280) 
       .centerCrop() 
       .crossFade() 
       .into(mImageview); 
     } 
     else { #What is good for this space? } 
    } 

我的代码做什么，如果用户点击mGetImageFromGalleryButton在GalleryFragment，用户可以去图库并选择一张图片，然后回到GalleryFragment与该图片的uri。

问题： 如果用户点击mGetImageFromGalleryButton等去画廊，但不要选择任何图片，然后在Android后退按钮时，Error message我上面说的发生了。所以，我想我必须修改public void onActivityResult的if子句。如果我认为是正确的，有什么好的else { #What is good for this space? }你能帮助我吗？

Answer 1

当您不选择任何图像时，数据为空。这就是它给出错误的原因。如果您的数据不为空，请在您的代码周围添加条件。

E.g

if(data != null){ 

    //Proceed with your image crop etc 

} 

Answer 2

@Override public void onActivityResult(int requestCode, int resultCode, Intent data) 
{ 
    Uri returnUri = data.getData(); 
    switch (requestCode) 
    { 
    case 1000: 
    if (resultCode == RESULT_OK && returnUri != null) 
    { 
     Bitmap bitmapImage = null; 
     try 
     { 
      bitmapImage = MediaStore.Images.Media.getBitmap(getActivity().getContentResolver(), returnUri); 
     } 
     catch (IOException e) 
     { 
      e.printStackTrace(); 
     } 
     mImageview.setImageBitmap(bitmapImage); 
     Glide.with(this) 
     .load(returnUri) 
     .override(1280, 1280) 
     .centerCrop() 
     .crossFade().into(mImageview); 
    } 
    break; 

    default: 
    super.onActivityResult(requestCode, resultCode, data); 
    break; 
    } 
}//onActivityResult