signin.java

/**
     * a public method to handel the user sign in event from the auth fragment
     *
     * @param email a string holds the user email address
     * @param password a string holds the user text password
     * @param view a view holds the auth widgets to hide
     */
    public void handleSignIn(String email, String password, final View view){
        showProgress(true,view);
        FirebaseUtils.auth.signInWithEmailAndPassword(email, password).addOnCompleteListener(
                new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        if (task.isSuccessful()){
                            startChatActivity();
                        }else{
                            // displaying an error message toast
                            Toast.makeText(LauncherActivity.this, task.getException().getMessage(), Toast.LENGTH_SHORT).show();
                            showProgress(false,view);
                        }
                    }
                }
        );
    }