矩形面积

package mytext;

public class juxing {
    
        juxing()
        {
        
        }
    
        juxing(String jx)
        {
            String juxing = jx;
        
                
        }
        String juxing;
    
        double chang;
    
        double kuan;
    
        double mj;

        double mianji(double chang,double kuan){ 
            
            return mj= chang*kuan;
        }
        
        public static void main (String[] args){
            
           juxing jx = new juxing();
                
            jx.chang = 10;
            
            jx.kuan = 5;
            
            jx.mj = jx.chang * jx.kuan;
            
            System.out.println("矩形的面积= "+jx.mj);
            
            
           }
            
            
        }