Java 如何使浮动按钮消失？

我有一个简单的浮动按钮，打开相机，然后在主活动中显示图像

我想在用户检索图像结果后立即删除该浮动按钮，因此它应该在

scannedImageView.setImageBitmap（位图）

我尝试使用

btnFloat.setVisibility（View.GONE）
main活动

ImageView scannedImageView;

public void init() {
FloatingActionButton fab = findViewById(R.id.fab_capture);
}

 protected void onActivityResult(int requestCode, int resultCode, Intent data) {
     super.onActivityResult(requestCode, resultCode, data);
     if (resultCode == Activity.RESULT_OK && data != null) {
         if (requestCode == OPEN_THING) {
             Uri uri = data.getExtras().getParcelable(ScanConstants.SCANNED_RESULT);
             Bitmap bitmap = null;
             try {
                 bitmap = MediaStore.Images.Media.getBitmap(getContentResolver(), uri);
                 getContentResolver().delete(uri, null, null);
                 scannedImageView.setImageBitmap(bitmap);
               //btnFloat.setVisibility(View.GONE);
                 FileOutputStream outputStream = null;
                 File sdCard = new File(getExternalFilesDir(null).getAbsolutePath());
                 File directory = new File (sdCard.getAbsolutePath() +"/Scan Documents");
                 directory.mkdir();

                 String filename = String.format("d.jpg", System.currentTimeMillis());
                 File outFile = new File(directory, filename);

                 Toast.makeText(this, "Image Saved Successfully", Toast.LENGTH_SHORT).show();

                 Intent intent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
                 intent.setData(Uri.fromFile(outFile));
                 sendBroadcast(intent);

                 try{
                     outputStream = new FileOutputStream(outFile);
                     bitmap.compress(Bitmap.CompressFormat.JPEG, 100, outputStream);
                     outputStream.flush();
                     outputStream.close();

                 }catch (FileNotFoundException e)
                 {
                     e.printStackTrace();
                 }
             } catch (IOException e) {
                 e.printStackTrace();
             }
         }
     }
 }

使FloatingActionButton成为全局成员变量，然后可以访问
它在onActivityResult

public class MyActivity extends Activity {
 ...
FloatingActionButton fab;

  @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    fab = findViewById(R.id.fab_capture);
}



 protected void onActivityResult(int requestCode, int resultCode,
         Intent data) {
  ...
    fab.hide();
   ...
 }
}

使FloatingActionButton成为全局成员变量，然后可以访问
它在onActivityResult

public class MyActivity extends Activity {
 ...
FloatingActionButton fab;

  @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    fab = findViewById(R.id.fab_capture);
}



 protected void onActivityResult(int requestCode, int resultCode,
         Intent data) {
  ...
    fab.hide();
   ...
 }
}