java，编写一个矩形类，

package org.hanqi.pn0120;

public class JuXing {
double chang;
double kuan;
JuXing(double chang,double kuan)
{
this.chang=chang;
this.kuan=kuan;
}
//计算面积
double getMianJi()
{
return this.chang*this.kuan;
}
public static void main(String[] args)
{
JuXing myJX=new JuXing(10,5);
System.out.println(""+myJX.getMianJi());

}

}