When trying to delete last character, I'm getting an error 

```
Cant resolve method substring(int. int) 

```

I'm trying to achieve this for `TextView` is that an issue, I'm not sure as I was able to use `.append()` and `.setText()` methods on it successfully.

Is there a chance that some sort of android import is required to use substring method? 

```
getUserIn_DEL = (Button) findViewById(R.id.userIn_DEL);
getUserAnswer = (TextView) findViewById(R.id.userInAnswer);

getUserIn_DEL.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        if (!getUserAnswer.getText().equals("?")) {
            String getUserAnswerString = getUserAnswer.getText().toString();
            int userAnswerLength = getUserAnswerString.length();
            int userAnswerLengthMin = userAnswerLength - 1;
            int userAnswerLengthMax = userAnswerLength + 1;
            getUserAnswerString = substring(userAnswerLengthMin, userAnswerLengthMax);
            getUserAnswer.setText(getUserAnswerString);
        }
    }
});

```