java练习---12

 public class L1106 {

     public static void main(String[] args) {
         // TODO Auto-generated method stub
         TestDemo circle1 = new TestDemo();
         double area=circle1.getArea();
         System.out.println(area);
         TestDemo circle2=new TestDemo(10);
         System.out.println(circle2.getArea());
         System.out.println(circle1.getPerimeter());
         System.out.println(circle2.getPerimeter());
         double ridius=10;
         double areaCircle=Math.PI*ridius*ridius;
         System.out.println(areaCircle);
         circle2.setRadius(5);
         System.out.println(circle2.getArea());
     }

 }

 public class TestDemo {

 private double radius;

     public TestDemo(double radius) {
         this.radius = radius;
     }
     public TestDemo() {
         this.radius = 1.0;
     }
     public double getArea() {
         return Math.PI * radius * radius;
     }
     public double getPerimeter() {
         return 2 * Math.PI * radius;
     }
     public void setRadius(double newRadius) {
         this.radius = newRadius;
     }
 }

 package cn.TV;
 import java.util.Scanner;
 public class L {
     public int channel = 1;
     public int volume = 50;
     public boolean power = false;

     public void powerOn() {
         power = true;
         System.out.println("欢迎使用LLTV,电视机已启动！");
     }
     public void powerOff() {
         power = false;
         System.out.println("Loading...");
         System.out.println("**关机**");
     }
     public int getChannel() {
         return channel;
     }
     public void setChannel(int channel) {
         if(power) {
             if(channel >= 1 && channel <= 100) {
                 this.channel = channel;
                 System.out.println("正在收看LLTV：" + channel );
             }else {
                 System.out.println("您并未购买此频道信号！");
             }
         }else {
             System.out.println("请检查您的电视信号接收线是否正常！");
         }
     }
     public void channelUp() {
         if(power  && channel < 100)
             channel++;
         else System.out.println("+++无信号+++");
     }
     public void channelDown() {
         if(power  && channel > 1)
             channel--;
         else System.out.println("---无信号---");
     }
     public void volumeUp() {
         if(power && volume < 100) {
             volume++;
             System.out.println("当前音量为：" + volume + "%！");
         }else System.out.println("音量已达最大值");
     }
     public void volumeDown() {
         if(power && volume > 0) {
             volume--;
             if(volume == 0)
                 System.out.println("电视机已静音！");
         }

     }
     public static void main(String[] args) {
         // TODO Auto-generated method stub
         Scanner input = new Scanner(System.in);
         L lltv = new L();
         lltv.powerOn();
         System.out.print("手动输入频道序号：");
         int temp = Integer.valueOf(input.nextLine());;
         lltv.setChannel(temp);
         lltv.getChannel();
         lltv.volumeUp();
         lltv.volumeDown();
     }
 }