练习9(第九章习题)
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package cn.ch.w; public class TestSimpleCircle { private double radius; // 构造方法,有参构造 public void Circle(double radius) { this.radius = radius; } //方法的重载,参数不同 // 构造方法,无参构造 public void 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 cn.ch.w; public class DemoCircle { public static void main(String[] args) { TestSimpleCircle circle1=new TestSimpleCircle(); double area=circle1.getArea(); System.out.println(area); TestSimpleCircle circle2=new TestSimpleCircle(); 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
package cn.ch.w; public class SimpleCircle { private double radius; public SimpleCircle() { this.radius=1; } public SimpleCircle(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) { SimpleCircle cir1=new SimpleCircle(); System.out.println("半径是"+cir1.radius+"面积是"+cir1.getArea()); SimpleCircle cir2=new SimpleCircle(10); System.out.println("半径是"+cir2.radius+"面积是"+cir2.getArea()); } }
9-3
package cn.ch.w; public class TV { public int channel=1; public int volumeLevel=1; public boolean on=false; public TV() { } public void turnOn() { on =true; System.out.println("电视已开启!!"); } public void turnOff() { on=false; System.out.println("电视已关闭!!"); } public int getChannel() { return channel; } public void setChannel(int channel) { if(on) { System.out.println("电视机已开,可以调试了。"); if(channel>=1&&channel<=120) { this.channel = channel; System.out.println("频道已在"+channel+" 台"); }else { System.out.println("频道不存在!!"); } }else { System.out.println("白痴主人电视开启才可以调试"); } } public int getVolumeLevel() { return volumeLevel; } public void setVolumeLevel(int volumeLevel) { if(on) { System.out.println("电视已开,声音已可调试"); if(volumeLevel>=1&&volumeLevel<=7) { this.volumeLevel = volumeLevel; System.out.println("声音设置成了 "+volumeLevel+" 大小"); } }else { System.out.println("白痴主人电视开启才可以调试"); } } 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 cn.ch.w; public class testTV { public static void main(String[] args) { TV tv1=new TV(); tv1.turnOff(); tv1.setChannel(30); tv1.setVolumeLevel(3); TV tv2=new TV(); tv2.turnOn(); System.out.println("电视节目是"+tv2.channel+"声音是"+tv2.volumeLevel); tv2.channelUp(); System.out.println("电视节目是"+tv2.channel+"声音是"+tv2.volumeLevel); tv2.channelUp(); System.out.println("电视节目是"+tv2.channel+"声音是"+tv2.volumeLevel); tv2.channelUp(); System.out.println("电视节目是"+tv2.channel+"声音是"+tv2.volumeLevel); tv2.volumeUp(); System.out.println("电视节目是"+tv2.channel+"声音是"+tv2.volumeLevel); tv2.volumeUp(); System.out.println("电视节目是"+tv2.channel+"声音是"+tv2.volumeLevel); tv2.volumeUp(); System.out.println("电视节目是"+tv2.channel+"声音是"+tv2.volumeLevel); } }
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