/*圆的类*/
public class R {
private double radius; // 构造方法,有参构造
public R(double radius) {
this.radius = radius;
}
//方法的重载，参数不同
// 构造方法，无参构造
public R() {
this.radius = 1;
} // 求圆面积的方法
public double getArea() {
return radius * radius * Math.PI; }
//求圆的周长
public double getPerimeter() {
return 2 * Math.PI * radius;
}
public void setRadius(double newRadius) {
this.radius=newRadius;
} }
public class TR {
public static void main(String[] args) {
R circle1=new R();
double area=circle1.getArea();
System.out.println(area);
R circle2=new R(20);
System.out.println(circle2.getArea());
System.out.println(circle1.getPerimeter());
System.out.println(circle2.getPerimeter());
double ridius=8;
double areaCircle=Math.PI*ridius*ridius;
System.out.println(areaCircle);
circle2.setRadius(10);
System.out.println(circle2.getArea());
}
}
/*圆类的和并*/
public class TR { private double radius;
public TR() {
this.radius=1;
}
public TR(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) {
TR cir1=new TR();
System.out.println("The area of the circle of radius "+cir1.radius+" is "+cir1.getArea());
TR cir2=new TR(100);
System.out.println("The area of the circle of radius "+cir2.radius+" is "+cir2.getArea());
} }
/*造电视*/
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("电视已启动");
}
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("电视启动可以换台。");
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("电视关闭不能换台");
}
}
public int getVolumeLevel() {
return volumeLevel;
}
public void setVolumeLevel(int volumeLevel) {
if(on) {
System.out.println("电视启动可调声音");
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("电视关闭不能调声音");
} }
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--;
}
}
}
public class TextTV {
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("CCTV1's channel is "+tv2.channel+" and volume is "+tv1.volumeLevel);
tv2.channelUp();
System.out.println("CCTV2's channel is "+tv2.channel+" and volume is "+tv2.volumeLevel);
tv2.channelUp();
System.out.println("CCTV3's channel is "+tv2.channel+" and volume is "+tv2.volumeLevel);
tv2.channelUp();
System.out.println("CCTV4's channel is "+tv2.channel+" and volume is "+tv2.volumeLevel);
}
}