How to check if a file exists in Firebase storage from your android application?

Question

I am developing android application where a user clicks image, it gets stored in firebase, cloud functions process this image and stores the output back in the firebase in the form of text file. In order to display the output in android, application keeps checking for output file if it exists or not. If yes, then it displays the output in the application. If no, I have to keep waiting for the file till it is available.

I'm unable to find any documentation for checking if any file is exists in Firebase or not. Any help or pointers will be helpful.

Thanks.

Answer 1

You can use getDownloadURL which returns a Promise, which can in turn be used to catch a "not found" error, or process the file if it exists. For example:

    storageRef.child("file.png").getDownloadURL().then(onResolve, onReject);

function onResolve(foundURL) { 
//stuff 
} 
function onReject(error){ 
//fill not found
console.log(error.code); 
}

Updated

This is another simpler and cleaner solution.

storageRef.child("users/me/file.png").getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
    @Override
    public void onSuccess(Uri uri) {
        // Got the download URL for 'users/me/profile.png'
    }
}).addOnFailureListener(new OnFailureListener() {
    @Override
    public void onFailure(@NonNull Exception exception) {
        // File not found
    }
});