类

1先创建一个类

package lianxi;

public class lei {
    
    //属性
    //成员变量
    
    //品牌
    String PinPai;
    
    //速度
    double SuDu;
    
    //油耗
    double YouLiang =0;
    
    
    //行为
    //方法  void-没有返回值，如果有返回值，要写明返回值的数据类型
    //加油
    void jiaYou(double yl){
        YouLiang+=yl;
        System.out.println("这次加了"+yl+"升油，车的当前油量为 "+YouLiang);
    }
        double CaoLiang=50;
        
        double NaiLiang;
        
        String MingZi="牛XX";
        void chi(double y2){
            CaoLiang-=y2;
            NaiLiang+=y2;
            //System.out.println("这次吃了"+y2+"吨草，产了"+y2+"吨奶");
        }
            String ShuaiGe="张昊哲";
            String YouduoShuai="帅的惊天动地";
            double GeijiFen;
            void hao(double y2){
                GeijiFen+=y2;
            }
        
            String CheMing;
            
            double JiaGe;
            
            double YouHao;
            
            double JiaSu;
            
            double GongLi;
            void jg(double x1){
                JiaGe=x1;
            }
            void yh(double x2){
                YouHao=x2;
            }
            void js(double x3){
                JiaSu=x3;
                
                //父类
                Object o;//最大的父类
                
                
                
            }
            
}

2在另一个类里面可以直接用

package lianxi;

public class shiyonglei {

    public static void main(String[] args) {
        
        //实例化lei
        lei BMW=new lei();    
        BMW.PinPai="宝马";
        System.out.println("车的品牌="+BMW.PinPai);
        BMW.jiaYou(40);
        System.out.println("车的品牌="+BMW.PinPai+",当前油量="+BMW.YouLiang);
        
        lei CN=new lei();
        CN.chi(30);
        System.out.println(CN.MingZi+" 吃了30吨草，还剩"+
        CN.CaoLiang+"吨"+"产了"+CN.NaiLiang+"吨奶");
        
        
        lei CC=new lei();
        CC.hao(100);
            System.out.println("谁最帅?答："+CC.ShuaiGe);
            System.out.println("有多帅?答："+CC.YouduoShuai);
            System.out.println("给几分?答："+CC.GeijiFen);
            
        lei car=new lei();
        car.CheMing="宝驴";
        System.out.println("车名："+car.CheMing);
        car.jg(100);
            System.out.println("车的价格="+car.JiaGe);
        car.yh(8.5);
        System.out.println("车的油耗="+car.YouHao);
        car.js(12.75);
        System.out.println("车的加速="+car.JiaSu);
        
        
        car.CheMing="宝猪";
        System.out.println("车名："+car.CheMing);
        car.jg(98.434);
            System.out.println("车的价格="+car.JiaGe);
        car.yh(4.32);
        System.out.println("车的油耗="+car.YouHao);
        car.js(11.435);
        System.out.println("车的加速="+car.JiaSu);
            
            
            
    }

}