Android sample . When buntton is clicked , it displays message with Toast.

activity_main.xml

<RelativeLayout 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"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:text="@string/hello_world" />
    <Button
        android:id="@+id/button0"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/toast"
        android:layout_gravity="center">
 </Button>
    
    

</RelativeLayout>

MainActivity.java

package com.example.andtoast;


import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends Activity implements OnClickListener{

	private Button button0;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		button0=(Button)findViewById(R.id.button0);
		button0.setOnClickListener(this);

	}

	public void onClick(View v){
		Toast.makeText(this, "ボタンが押されました。", Toast.LENGTH_LONG).show();
    }	
	

}

strings.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <string name="app_name">AndToast</string>
    <string name="hello_world">Hello world!</string>
    <string name="toast">Toast!</string>
    <string name="menu_settings">Settings</string>

</resources>