无法让Firebase识别已经输入的用户名。下面的代码显示我正在尝试将输入的用户名与数据库的DataSnapshot进行比较。该代码似乎没有拾取输入的用户名。代码是否错误？

private boolean mSwitch = false;

public void checkInfo(View view){

    checkUsernameIsUnique();
    checkInformation();

    if(mSwitch) {
        Intent intent = new Intent(getApplicationContext(), MenuActivity.class);
        saveUserInformation();
        startActivity(intent);
    }
}

public void checkUsernameIsUnique(){

    String username = Username.getText().toString().trim();

    DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
    DatabaseReference usernameRef = rootRef.child("user_profile_info").child(userID);
    Query checkName = usernameRef.equalTo(username);
    checkName.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            String name = Username.getText().toString().trim();
            for (DataSnapshot ds : dataSnapshot.getChildren()) {
                if(name.equals(ds.child("username").getValue(String.class))){

                    Username.setError("Username Taken");
                    Username.requestFocus();

                } else {
                    Toast.makeText(ProfileActivity.this, "Registered User", Toast.LENGTH_SHORT).show();
                    mSwitch = true;
                }
            }
        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {

        }
    });

    if(Username.getText().toString().equals("")){

        Username.setError("A Username is Required");
        Username.requestFocus();

    }

    if(Username.length() < 5){

        Username.setError("Username must be 5 characters minimum");
        Username.requestFocus();

    }
}

在按钮上单击，我希望能够将用户引导到该错误，并且在该错误唯一之前，不应将该页面推送到下一个活动。

JSON树（如果有帮助）

"user_profile_info" : {
    "8FUV95JorVT26Gd1QFNUbxEf8O93" : {
      "date_of_birth" : "2/5/1925",
      "diet" : "Moderate",
      "drinker" : "No",
      "education" : "Masters Degree",
      "exercise" : "3 - 5 Hours a Week",
      "forename" : "Ben",
      "gender" : "Male",
      "have_alzheimers" : "No",
      "have_diabetes" : "No",
      "have_parkinsons" : "No",
      "history_alzheimers" : "No",
      "history_diabetes" : "No",
      "history_parkinsons" : "No",
      "marital_status" : "Single",
      "smoker" : "No",
      "surname" : "Dover",
      "username" : "Maturity101"
    }