Firebase Android: How to cancel download?

Question

How can I cancel my downloading task from Firebase?

I want to cancel the download whenever I click somewhere off the ProgressDialog.

Here is the part where my Download Activity ExamesActivity.java is. It looks like:

//Download the File on Button(Download) click:
 bDownload.setOnClickListener(new View.OnClickListener() {
 @Override
 public void onClick(View v) {
 //Initalizing teh Spinner-to-String functions:
 Grade = spClasse.getSelectedItem().toString();
 Type = spEpoca.getSelectedItem().toString();
 Subject = spDisciplina.getSelectedItem().toString();
 Year = spAno.getSelectedItem().toString();
 //Download the File:
 //First Check if ON the Spinner, everything is choosen. It should be. If not, show error Toast.
 if (Grade.equals("...") | Type.equals("...") | Disciplina.equals("...") | Year.equals("..."){
 //Show the The Error Toast:
 Toast.makeText(ExamesActivity.this, "everything shall be choosen", Toast.LENGTH_SHORT).show();
 } else { //What the dir would look like: "Subject/Grade/Year-Type.extension"
 pdfRef = mStorageRef.child(Subject + "/" + Grade + "/" + Year + "-" + Type + ".pdf");
 File root = android.os.Environment.getExternalStorageDirectory();
 File dir = new File(root.getAbsolutePath() + "/Exams-App/");
 //Show the ProgressDialog while downloading:
 progressDialog.show();
 if (!dir.exists()) {
 dir.mkdirs();
 }
 localFile = new File(dir, Subject + "-" + Year + "-" + Grade + "-" + Type + ".pdf");
 pdfRef.getFile(localFile).addOnSuccessListener(new OnSuccessListener<FileDownloadTask.TaskSnapshot>() {
 @Override
 public void onSuccess(FileDownloadTask.TaskSnapshot taskSnapshot) {
 // Local temp file has been created
 progressDialog.dismiss();
 Toast.makeText(ExamesActivity.this, "Exam was successfully downloaded!️", Toast.LENGTH_SHORT).show();
 }
 }).addOnFailureListener(new OnFailureListener() {
 @Override
 public void onFailure(@NonNull Exception exception) {
 // Handle any errors
 progressDialog.dismiss();
 Toast.makeText(ExamesActivity.this, "Exam not found on the server.", Toast.LENGTH_LONG).show();
 }
 }).addOnProgressListener(new OnProgressListener<FileDownloadTask.TaskSnapshot>() {
 @Override
 public void onProgress(FileDownloadTask.TaskSnapshot taskSnapshot) {
 //Some math to get the Percentage of the Download :)
 double progressPercentage = (100.0 * taskSnapshot.getBytesTransferred()) / taskSnapshot.getTotalByteCount();
 double size = (taskSnapshot.getTotalByteCount()) / (1000000);
 progressDialog.setMessage("PDF Size: " + (size) + " - " + ((int) progressPercentage) + "% - Click away to cancel the download.");
 }
 });
 }
 }
 });

Answer 1

pdfRef.[getFile][1](localFile) returns a FileDownloadTask. This object is a subclass of CancellableTask, which has a cancel() method. You will need to hold a reference to this task and call its cancel method to cancel the download.

• Jozef: Is there also any way to cancel getMetadata call? It returns com.google.android.gms.tasks.Task so no cancel() method is available.

Answer 2

Here is the solution I implemented:

>> On the OnProgressListener, I created a _storageTask variable of StorageTask type and stored the snapshot's task. Also, made the variable globally accessible.

....
StorageTask _storageTask; //global variable
..... 
 .addOnProgressListener(snapshot -> { _storageTask = snapshot.getTask()});
....

>> Created a method cancelUploading() which can be called when needed to cancel the uploading process.

private void cancelUploading()
{
 //Cancel the uploading process to the firebase storage.
 _storageTask.cancel();
 _storageTask.addOnCanceledListener(() -> Toast.makeText(AssignAnnounceActivity.this, "Uploading", Toast.LENGTH_SHORT).show());
}

NB: You can use that method whenever you need to cancel uploading process.