作业9.

 圆的面积和周长    

——9.1

package kk;

public class circle {
     private double radius;

        // 构造方法,有参构造
        public circle(double radius) {
            this.radius = radius;
        }
        //方法的重载，参数不同
        // 构造方法，无参构造
        public circle() {
            this.radius = 1;
        }

        // 求圆面积的方法
        public double getArea() {
            return radius * radius * Math.PI;

        }

        // 求圆周长的方法
        public double getPerimeter() {
            return 2 * Math.PI * radius;
        }
        public void setRadius(double newRadius) {
            this.radius=newRadius;
        }
}

package kk;

public class Dmc {
      public static void main(String[] args) {
            circle circle1=new circle();
            double area=circle1.getArea();
            System.out.println(area);
            circle circle2=new circle(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());
            
        }
}

——9.2    (合并)

package kk;

public class Scircle {
     private double radius;
        public Scircle() {
            this.radius=1;
        }
        public Scircle(double radius){
            this.radius=radius;
        }
        public double getArea() {
            return Math.PI*radius*radius;
        }
        public double getPerimeter() {
            return 2*Math.PI*radius;
        }
        public static void main(String[] args) {
            Scircle cir1=new Scircle();
            System.out.println("The area of the circle of radius "+cir1.radius+" is "+cir1.getArea());
            Scircle cir2=new Scircle(10);
            System.out.println("The area of the circle of radius "+cir2.radius+" is "+cir2.getArea());
        }
}

——9.3    (TV)

package kk;
public class TV {
    public int channel=1;
    public int volumeLevel=1;
    public boolean on=false;
    public void turnOn() {
        on =true;
        System.out.println("地址为"+new TV());
        System.out.println("号的电视已经打开");
    }
    public void turnOff() {
        on=false;
        System.out.println("电视已经关闭");
    }
    public int getChannel() {
        return channel;
    }
    public void setChannel(int channel) {
        if(on) {
            System.out.println("电视机已开，可开始调台");
            if(channel>=1&&channel<=120) {
                this.channel = channel;
                System.out.println("频道已经调到 "+channel+" 号台");
            }else {
                System.out.println("你要调的频道不存在");
            }
        }else {
            System.out.println("电视机关着的时候不能调台");
        }
    }
    public int getVolumeLevel() {
        return volumeLevel;
    }
    public void setVolumeLevel(int volumeLevel) {
        if(on) {
            System.out.println("电视机已开，声音大小可调");
            if(volumeLevel>=1&&volumeLevel<=7) {
                this.volumeLevel = volumeLevel;
                System.out.println("声音的大小设置成 "+volumeLevel);
            }
            else {
                System.out.println("音量大小超过范围");
            }
        }else {
            System.out.println("电视机关着的时候不能调声音");
        }
        
    }
    public void channelUp() {
        if(on&&channel<120) {
            channel++;
        }
    }
    public void channelDown() {
        if(on&&channel>1) {
            channel--;
        }
    }
    public void volumeUp() {
        if(on&&volumeLevel<7) {
            volumeLevel++;
        }
    }
    public void volumeDown() {
        if(on&&volumeLevel>1) {
            volumeLevel--;
        }
    }
    
    
}

package kk;

public class CTV {
     public static void main(String[] args) {
       TV tv1=new TV();
       tv1.turnOn();
       tv1.setChannel(77);
       tv1.setVolumeLevel(9);      
       TV tv2=new TV();
       tv2.turnOn();
       System.out.println("TV2's channel is "+tv2.channel+" and volume is "+tv2.volumeLevel);
       tv2.channelUp();
       System.out.println("TV2's channel is "+tv2.channel+" and volume is "+tv2.volumeLevel);
       tv2.channelUp();
       System.out.println("TV2's channel is "+tv2.channel+" and volume is "+tv2.volumeLevel);
       tv2.channelUp();
       System.out.println("TV2's channel is "+tv2.channel+" and volume is "+tv2.volumeLevel);
       tv2.volumeUp();
       System.out.println("TV2's channel is "+tv2.channel+" and volume is "+tv2.volumeLevel);
       tv2.volumeUp();
       System.out.println("TV2's channel is "+tv2.channel+" and volume is "+tv2.volumeLevel);
       tv2.volumeUp();
       System.out.println("TV2's channel is "+tv2.channel+" and volume is "+tv2.volumeLevel);
             
   }

}