Plzz help me to solve te problem. This is the line:
String thumb_download_url=thumb_task.getResult().getDownloadUrl().toString();
And the code is as below:
StorageReference filepath=mStorageReference.child("profile_image").child(uid+".jpg"); final StorageReference thumb_file_path=mStorageReference.child("profile_image").child("thumbs").child(uid+".jpg");
//------STORING IMAGE IN FIREBASE STORAGE--------
            filepath.putFile(resultUri).addOnCompleteListener(new OnCompleteListener<UploadTask.TaskSnapshot>() {
    @Override
    public void onComplete(@NonNull Task<UploadTask.TaskSnapshot> task) {
        if(task.isSuccessful()){
            @SuppressWarnings("VisibleForTests")
            final String downloadUrl=  task.getResult().getDownloadUrl().toString();
            UploadTask uploadTask = thumb_file_path.putBytes(thumb_bytes);
            //---------- STORING THUMB IMAGE INTO STORAGE REFERENCE --------
            uploadTask.addOnCompleteListener(new OnCompleteListener<UploadTask.TaskSnapshot>() {
                @Override
                public void onComplete(@NonNull Task<UploadTask.TaskSnapshot> thumb_task) {
                    @SuppressWarnings("VisibleForTests")
                    String thumb_download_url=thumb_task.getResult().getDownloadUrl().toString();
                    if(thumb_task.isSuccessful()){
                        Map update_HashMap=new HashMap();
                        update_HashMap.put("image",downloadUrl);
                        update_HashMap.put("thumb_image",thumb_download_url);
                        //--------ADDING URL INTO DATABASE REFERENCE--------
                        mDatabaseReference.updateChildren(update_HashMap).addOnCompleteListener(new OnCompleteListener<Void>() {
                            @Override
                            public void onComplete(@NonNull Task<Void> task) {
                                if(task.isSuccessful()){
                                    mProgressDialog.dismiss();
                                    Toast.makeText(SettingActivity.this, "Uploaded Successfuly...", Toast.LENGTH_SHORT).show();
                                }
                                else{
                                    mProgressDialog.dismiss();
                                    Toast.makeText(getApplicationContext(), " Image is not uploading...", Toast.LENGTH_SHORT).show();
                                }
                            }
                        });
                    }
                    else{
                        mProgressDialog.dismiss();
                        Toast.makeText(getApplicationContext(), " Error in uploading Thumbnail..", Toast.LENGTH_SHORT).show();
                    }
                }
            });