1.

复制代码
public class Test{
    public static void main(String[] args){
        int i;
        for(i = 1;i <= 5;i++){
        System.out.println("Welcome to java"); 
        }
    }
}
 
复制代码
public class Test{
    public static void main(String[] args){
            System.out.println("    J     A    V     V   A ");
            System.out.println("    J    A A    V   V   A A ");
            System.out.println(" J  J   A A A    V V   A A A ");
            System.out.println("  J J  A     A    V   A     A ");
    }
}

 

2.

public class AverageSpeed{

 public static void main(String[]args){

double speedkm =60/(45.5/14);

double speedm = speedkm /1.6;

system.out.println（“averagespeed = ”+speedm + "m/h"）

}

 

 

 

}

 

 

3.

public class Circle{
private double r;
public  Circle(double r){
this.r =r;
}
public  double getLength(){
return 2*Math.PI*r;
}
public  double getArea(){
return Math.PI*r*r;
}
}