Android Studio를 활용한 안드로이드 프로그래밍 연습문제 322p 5번 문제

MainActivity.XML

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:gravity="center">

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="토스트 보내기"
        android:id="@+id/btn"
        />
</LinearLayout>

JAVA

package com.example.a322p5;

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.ImageView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    Button btn;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn = (Button)findViewById(R.id.btn);

        btn.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View v)
            {
                Toast msg = new Toast(getApplicationContext());
                ImageView img = new ImageView(getApplicationContext());
                img.setImageResource(R.drawable.ic_launcher_background);
                msg.setView(img);

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

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