(Android) EditText for Phone number style (XXX-XXXX-XXXX)

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <EditText
        android:id="@+id/phone_number"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:phoneNumber="true"
        android:inputType="phone"
        <!-- input string length for Koean phone number format. XXX-XXXX-XXXX -->
        android:maxLength="13"/>
    <Button
        android:id="@+id/getNumber"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/get_button"/>
    <TextView
        android:id="@+id/output_number"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <TextView
        android:id="@+id/output_number_refinded"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
        
</LinearLayout>

EditTextPhoneNumberActivity.java

// impport, package name skipped...

public class EditTextPhoneNumberActivity extends Activity implements View.OnClickListener{

    private EditText mPhoneNumber;
    private TextView mOutputNumber;
    private TextView mOutputNumber_refined;
    private Button mBtn;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mPhoneNumber = (EditText)findViewById(R.id.phone_number);
        mBtn = (Button)findViewById(R.id.getNumber);
        mOutputNumber = (TextView)findViewById(R.id.output_number);
        mOutputNumber_refined = (TextView)findViewById(R.id.output_number_refinded);

        mPhoneNumber.addTextChangedListener(new PhoneNumberFormattingTextWatcher());   
        // mPhoneNumber.addTextChangedListener(new PhoneNumberFormattingTextWatcher("KR")); // API Level 21. Country Code
        
        mBtn.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case  R.id.getNumber :
                String tmp = mPhoneNumber.getText().toString();
                mOutputNumber.setText(tmp);  // Edit Text Value ( -, dash included)
                mOutputNumber_refined.setText(tmp.replace("-", "")); // split dash 
        }

    }
}