JAVA第九次作业

第一题

import java.util.Scanner;
 
public class Str {
static final  double PI=3.141592653589793;
	public static double add(double a,double b){
		return(a*b);
	}
	public static double add(double r){
		return(r*r*PI);
	}
	
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		System.out.println(PI);
		System.out.println(add(4.0000001));
		System.out.println(add(3.0,4.0));
	}
	}

第二题

public interface Te {
public void hello();
public void work();
}
 
class teacher implements Te{
 
	
	public void hello() {
		System.out.println("mike:同学们好");
	}
 
	
	public void work() {
		System.out.println("mike:老师开始上课");	
	}
	
}
class student implements Te{
 
	
	public void hello() {
		
		System.out.println("peter:老师好");
	}
 
 
	public void work() {
		System.out.println("peter:同学们开始记笔记");
	}
	
}
 
public class Cla {
 
	public static void main(String[] args) {
		// TODO Auto-generated method stub
Te[]a={new student(),new teacher()};
for(int i=1;i<a.length;i++){
	a[0].hello();
	a[1].hello();
	a[1].work();
	a[0].work();
}
	}
 
}

第三题

public interface IFather {
void smoking();
void goFishing();
}
public interface IMother {
void watchTV();
void cooking();
}
public class Me implements IFather,IMother {
 
	public void watchTV() {
	System.out.println("看电视");
		
	}
 
 
	public void cooking() {
		System.out.println("做饭");
		
	}
 
	
	public void smoking() {
		
		System.out.println("抽烟");
	}
 
 
	public void goFishing() {
	
		System.out.println("钓鱼");
	}
	public static void main(String[] args) {
	IFather father=new Me();
	IMother mother=new Me();
	System.out.println("儿子喜欢做的事有：");
	mother.watchTV();
	mother.cooking();
	father.smoking();
	father.goFishing();
 
	}
 
 
}