Not an enclosing class error Android Studio

Question

I am new in android development and do not have an in depth knowledge of Java. I am stuck on a problem for a long time. I am trying to open a new activity on button click. B

Answer 1

String user_email = email.getText().toString().trim();
firebaseAuth
    .createUserWithEmailAndPassword(user_email,user_password)
    .addOnCompleteListener(new OnCompleteListener() {
        @Override
        public void onComplete(@NonNull Task task) {
            if(task.isSuccessful()) {
                Toast.makeText(RegistraionActivity.this, "Registration sucessful", Toast.LENGTH_SHORT).show();
                startActivities(new Intent(RegistraionActivity.this,MainActivity.class));
            }else{
                Toast.makeText(RegistraionActivity.this, "Registration failed", Toast.LENGTH_SHORT).show();
            }
        }
    });