getDownloadUrl is not working

[Keown2000]

Here is my code:
private void uploadFile() {

    if (mImageUri != null) {
        StorageReference fileReference = mStorageRef.child(System.currentTimeMillis()
                + "." + getFileExtension(mImageUri));
        mUploadTask = fileReference.putFile(mImageUri)
                .addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
                    @Override
                    public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {

                        Handler handler = new Handler();
                        handler.postDelayed(new Runnable() {
                            @Override
                            public void run() {
                                mProgressBar.setProgress(0);
                            }
                        }, 500);
                        Toast.makeText(MainActivity.this, "Upload successful", Toast.LENGTH_LONG).show();
                        Upload upload = new Upload(mEditTextFileName.getText().toString().trim(),


                                taskSnapshot.getDownloadUrl().toString());


                        String uploadId = mDatabaseRef.push().getKey();
                        mDatabaseRef.child(uploadId).setValue(upload);
                    }
                })
                .addOnFailureListener(new OnFailureListener() {
                    @Override
                    public void onFailure(@NonNull Exception e) {
                        Toast.makeText(MainActivity.this, e.getMessage(), Toast.LENGTH_SHORT).show();
                    }
                })
                .addOnProgressListener(new OnProgressListener<UploadTask.TaskSnapshot>() {
                    @Override
                    public void onProgress(UploadTask.TaskSnapshot taskSnapshot) {
                        double progress = (100.0 * taskSnapshot.getBytesTransferred() / taskSnapshot.getTotalByteCount());
                        mProgressBar.setProgress((int) progress);
                    }
                });
    } else {
        Toast.makeText(this, "No file selected", Toast.LENGTH_SHORT).show();
    }
}

I have tried to implement get storage in front of it but still does not work..
can anyone help me ?

[Frank van Puffelen]

Determining the download URL requires a call to the server. Because of this, the call to getDownloadUrl() returns a Task that completes when the download URL comes back from the server. You'll need to call addSuccessListener() on it to wait for it to complete. See the documentation here and this answer on Stack Overflow.