java第九次作业：第九章例题3个

作业1：

例题9.1 制作圆类，根据圆的半径求出周长及面积

package com.swift;//抽象的方法构成类，把属性和方法进行封装public class Circle { // 两个方面一个是字段也称属性，另一个是方法，也称实现的功能 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; }}

圆类的展示类

package com.swift;public class DemoCircle { 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()); }}

作业2：

把上边的两个圆的类合并成一个类，并实现同样功能

package com.swift;public class SimpleCircle { private double radius; public SimpleCircle() {  this.radius=1; } public SimpleCircle(double radius){  this.radius=radius; } public double getArea() {  // TODO Auto-generated method stub  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("The area of the circle of radius "+cir1.radius+" is "+cir1.getArea());  SimpleCircle cir2=new SimpleCircle(10);  System.out.println("The area of the circle of radius "+cir2.radius+" is "+cir2.getArea()); }}

作业3：

例题9.3 造一台电视机，并且实现调频道和调声音大小功能

package com.swift;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("电视机已经打开了。"); } public void turnOff() {  on=false;  System.out.println("电视机已经关闭了。"); } public int getChannel() {  return channel; } public void setChannel(int channel) {  if(on) {   System.out.println("电视机已开，可以开始调台了。");   if(channel>=1&&channel<=120) {    this.channel = channel;    System.out.println("频道已经调到 "+channel+" 台");   }else {    System.out.println("你要调的频道不存在。");   }  }else {   System.out.println("电视机关着的时候是不能调台的");  } } public int getVolumeLevel() {  return volumeLevel; } public void setVolumeLevel(int volumeLevel) {  if(on) {   System.out.println("电视机已开，声音大小可调了");   if(volumeLevel>=1&&volumeLevel<=7) {    this.volumeLevel = volumeLevel;    System.out.println("声音的大小设置成了 "+volumeLevel+" 大小");   }  }else {   System.out.println("电视机关着的时候是不能调声音的");  }   } 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--;  } }  }

测试电视机的类

package com.swift;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("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);     }}

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原标题：java第九次作业：第九章例题3个

关键词：JAVA