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：

 1 package org.hanqi.pn0120;
 2 
 3 //公共的
 4 public class JuXing2 {
 5     double chang;
 6         double kuan;
 7 public JuXing2(double chang,double kuan)
 8     {
 9         this.chang=chang;
10         this.kuan=kuan;
11     }
12     
13     //计算面积
14     double getMianJi()
15     {
16         return this.chang*this.kuan;
17     }
18     
19     public static void main(String[] args)
20     {
21         JuXing2 myJX=new JuXing2(20,6);
22         myJX.chang=12;
23         
24         System.out.println("长="+myJX.chang);
25         
26         System.out.println("矩形的面积="+myJX.getMianJi());
27     }
28 
29 }