Pg168—2题 修改

package org.hanqi.pn0120;

public class JuXing {

    JuXing(double chang,double kuan)
    {
        this.chang=chang;

        this.kuan=kuan;
    }

    double chang;

    double kuan;

    double getMianJi()
    {
        return  this.chang*this.kuan;
    }
    public static void main(String[] args)
    {
        JuXing myJX=new JuXing(20,10);

        System.out.println("计算得到的面积=" +myJX.getMianJi());
    }

}

课后题修改