android - Toast 위치 랜덤으로 표출하기

<?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">

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="메세지 출력"/>

</LinearLayout>

package com.example.it.myapplication7_6;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Display;
import android.view.Gravity;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

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

        final Button button1 = (Button) findViewById(R.id.button1);

        button1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast tMsg = Toast.makeText(MainActivity.this, "토스트연습", Toast.LENGTH_SHORT);

                Display display = ((WindowManager) getSystemService(WINDOW_SERVICE)).getDefaultDisplay();
                int xOffset = (int) (Math.random() * display.getWidth());
                int yOffset = (int) (Math.random() * display.getHeight());

                tMsg.setGravity(Gravity.TOP | Gravity.LEFT, xOffset, yOffset);
                tMsg.show();
            }
        });
    }
}