作业题

package 面向对象编程;

public class jvxing {

    jvxing()
    {
        chang=10;
        kuan=9;
    }
    //属性
    double chang;
    double kuan;
    //行为
    void mianji()
    {
        System.out.println("矩形面积="+chang*kuan);
    }
    public static void main(String[] args) {
    
        jvxing myjvxing=new jvxing();
        myjvxing.mianji();//90.0
        myjvxing.chang=2;
        myjvxing.kuan=4;
        myjvxing.mianji();//8.0
    }

}