我的第一个JAVA程序——计算正方形面积

package all; class square{   private double side;//side边长   public void setside(double a)    { side=a;    }   public double getside()//返回边长    { return side;    }   public double area()//返回面积   { return side*side;   }} public class square1{  public static void main(String[] args) {out1 x,y;x=new out1();y=new out1();x.setside(2);y.setside(4);         System.out.println("x.side="+x.getside());System.out.println("y.side="+y.getside());System.out.println("x.area="+x.area());System.out.println("y.area="+y.area());}}