* R.java 리소스 저장 클래스

MainActivity.java
    button1
    button2

R.java(리소스의 주소값을 저장)
    button1
    button2

activity_main.xml
    button1
    button2

* R.java 를 보는 방법
Project Files로 변경
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app/build/generated/source/r/debug
/R.java 확인

* 환율계산
EditText :dollar
Button : button1
TextView : txtResult

* Container 와 Component
Container : 컴포넌트를 담을 수 있음

* Widget
view : 최상위 위젯

 

MainActivity.class

 

package com.example.choi.ex01;

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


//Activitiy : 화면 처리 클래스
public class MainActivity extends AppCompatActivity {
//화면을 생성

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

//버튼을 누르면 실행되는 method
 //android:onclick="onClick"
 // View v =new Button(...);
    public void onClick(View v){
//new Intent(현재 클래스 .this, 다음 화면 클래스 .class)

        Intent intent=null;

        switch(v.getId()){

            case R.id.button1:
                intent =new Intent(this, ImgeViewDemo.class);
                break;
            case R.id.button2:
                intent =new Intent(this, Exchange.class);
                break;
        }
        startActivity(intent);


    }

}

 

activity_main.xml

<?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="com.example.choi.ex01.MainActivity">

    <!--onClick ="버튼을 클릭했을 때 실행할 함수 이름-->

    <Button
        android:text="이미지뷰"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/button1"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:onClick="onClick" />

    <Button
        android:text="환율계산"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/button1"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginTop="29dp"
        android:onClick="onClick"
        android:id="@+id/button2" />


</RelativeLayout>

 

Exchange.class

 

package com.example.choi.ex01;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class Exchange extends AppCompatActivity {

    //1.위젯 선언
    EditText dollar;
    Button button;
    TextView txtResult;


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

        //2.위젯 생성
        //(형변환)findViewById(리소스 아이디)
        dollar =(EditText)findViewById(R.id.dollar);
        button=(Button)findViewById(R.id.button);
        txtResult=(TextView)findViewById(R.id.txtResult);

        //3.버튼 클릭 이벤트
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
    //EditText는 getText().toString() 을 해야 스트링으로 변환됨
     // String.foramt("출력형식", 출력할값)
                if(!dollar.getText().toString().equals("")){
    // Toast.makeText(출력할 클래스.this, "메시지", 출력옵션).show()
                    Integer intDollar
                            =Integer.parseInt(dollar.getText().toString());
                    int money =intDollar *  1100;
                    txtResult.setText(intDollar+"달러="+String.format("%,d",money)+"원입니다.");
                }else{
                    Toast.makeText(Exchange.this, "숫자를 입력하세요.", Toast.LENGTH_SHORT).show();
                }


            }
        });

    }




}

 

exchange.xml

<?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/exchange"
    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="com.example.choi.ex01.Exchange">

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="textPersonName"
        android:text=""
        android:ems="10"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginLeft="44dp"
        android:layout_marginStart="44dp"
        android:id="@+id/dollar"
        android:hint="달러를 입력하세요" />

    <Button
        android:text="환율계산"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/dollar"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginLeft="17dp"
        android:layout_marginStart="17dp"
        android:layout_marginTop="39dp"
        android:id="@+id/button" />

    <TextView
        android:text=""
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/button"
        android:layout_alignLeft="@+id/button"
        android:layout_alignStart="@+id/button"
        android:layout_marginLeft="12dp"
        android:layout_marginStart="12dp"
        android:layout_marginTop="63dp"
        android:id="@+id/txtResult" />


</RelativeLayout>