JAVA 객체지향 프로그래밍 Ⅰ 연습문제

TV 컨트롤 프로그램을 만들어보시오

public class TV {
	
	boolean power = false;
	int volume = 5; 
	int channel = 1;
	
	final int MIN_CHANNEL = 1;
	final int MAX_CHANNEL = 100;
	final int MIN_VOLUME = 0;
	final int MAX_VOLUME = 10;
	
	void powerMethod(){
		power = !power;
		System.out.println(power ? "TV 켜짐" : "TV 꺼짐");
	}
	
	void changeChannel(int channel){
		if(power){
			if(MIN_CHANNEL <= channel && channel <= MAX_CHANNEL){
				this.channel = channel;
                		//전역변수와 지역변수를 비교하기 위해 전역변수 앞에 this
			}
			System.out.println("채널. " + this.channel);
		}
	}
	
	void channelUp(){
		changeChannel(channel + 1); //코드를 재사용 한다.
	}
	
	void channelDown(){
		changeChannel(channel - 1);
	}
	
	void volumeUp(){
		if(power){
			if(volume < MAX_VOLUME){
				volume++;
			}
			showVolume();
		}
	}
	
	void voluemeDown(){
		if(power){
			if(MIN_VOLUME < volume){
				volume--;
			}
			showVolume();
		}
	}
	
	void showVolume(){
		System.out.print("음량. ");
		for(int i = MIN_VOLUME + 1; i <= MAX_VOLUME; i++){
			if(i <= volume){
				System.out.print("■");
			}else{
				System.out.print("□");
			}
		}
		System.out.println();
	}
	
	public static void main(String[] args) {
		TV tv = new TV();
		
		while(true){
			System.out.println("--------------------------");
			System.out.println("1.전원 2.채널변경 3.채널업 4.채널다운");
			System.out.println("5.볼륨업 6.불륨다운 0.종료");
			System.out.println("--------------------------");
			System.out.println("번호 입력>");
			int input = ScanUtil.nextInt();
			
			switch(input){
			case 1: tv.powerMethod(); break;
			case 2:
				System.out.println("변경할 채널 입력>");
				int ch = ScanUtil.nextInt();
				tv.changeChannel(ch);
				break;
			case 3: tv.channelUp(); break;
			case 4: tv.channelDown(); break;
			case 5: tv.volumeUp(); break;
			case 6: tv.voluemeDown(); break;
			case 0:
				System.out.println("종료되었습니다.");
				System.exit(0);
			}
		}		
		
	}