7.6实战练习2矩形

尝试编写一个矩形类，讲长与宽作为矩形类的属性，在构造方法中将长、宽初始化，定义一个成员方法求此矩形的面积。

package org.hanqi.pn0120;

public class Juxing {
    
    Juxing()
    {
        chang=15;
        
        kuan=10;
    }
    
    double chang;
    double kuan;
    
    
    
    void mianji()
    {
        System.out.println("mianji="+chang*kuan);
    }
    
    public static void main(String[] args) {
        
        Juxing myJuxing=new Juxing();
        
        myJuxing.mianji();
        
        

    }

}

 

修正：

package org.hanqi.pn0120;

//公共的
public class JuXing2 {
    double chang;
        double kuan;
public JuXing2(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)
    {
        JuXing2 myJX=new JuXing2(20,6);
        myJX.chang=12;
        
        System.out.println("长="+myJX.chang);
        
        System.out.println("矩形的面积="+myJX.getMianJi());
    }

}