class MainActivity

package org.androidtown.hello;

import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }


    public void onButton1Clicked(View v){
        Toast.makeText(this, "버튼이 클릭되었습니다.", Toast.LENGTH_SHORT).show();
    }


    public void onButton2Clicked(View v){
        Intent intent =new Intent(Intent.ACTION_VIEW, Uri.parse("http://m.naver.com"));
        startActivity(intent);
    }

    public void onButton3Clicked(View v){
        Intent intent=new Intent(Intent.ACTION_VIEW, Uri.parse("tel:010-1000-1000"));
        startActivity(intent);
    }

    public void onButton4Clicked(View v){
        Intent intent =new Intent(this, MenuActivity.class);
        startActivity(intent);
    }



}

 

R.layout.activity_main

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="org.androidtown.hello.MainActivity">

    <Button
        android:text="안녕"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/button"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:textSize="14sp"
        android:onClick="onButton1Clicked" />

    <Button
        android:text="시작2 - m.naver.com"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="17dp"
        android:id="@+id/button2"
        android:layout_below="@+id/button"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:onClick="onButton2Clicked"
        />

    <Button
        android:text="시작3 - tel"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="33dp"
        android:id="@+id/button3"
        android:onClick="onButton3Clicked"
        android:layout_below="@+id/button2"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />

    <Button
        android:text="시작4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="38dp"
        android:id="@+id/button4"
        android:onClick="onButton4Clicked"
        android:layout_below="@+id/button3"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />
</RelativeLayout>

 

 

 class MenuActivity

package org.androidtown.hello;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;

public class MenuActivity extends AppCompatActivity {

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



    public void onButton1Click(View v){
        finish();
    }


}

 

 

R.layout.activity_menu

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_menu"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="org.androidtown.hello.MenuActivity">

    <Button
        android:text="돌아가기"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginLeft="33dp"
        android:layout_marginStart="33dp"
        android:layout_marginTop="60dp"
        android:id="@+id/button"
        android:onClick="onButton1Click" />
</RelativeLayout>