方法重写及一些应用

1. 方法的重写(override/overriding)：重新写、覆盖

   • 发生在父子类中，方法名相同，参数列表相同

   • 重写方法被调用时，看对象的类型---------------new谁就调谁的，这是规定

     class 餐馆{
         void 做餐(){ 做中餐 }
     }
     //1)我还是想做中餐----------------------不需要重写
     class Aoo extends 餐馆{
     }
     //2)我想改做西餐------------------------需要重写
     class Boo extends 餐馆{
         void 做餐(){ 做西餐 }
     }
     //3)我想在中餐基础之上加入西餐------------需要重写(先super中餐，再加入西餐)
     class Coo extends 餐馆{
         void 做餐(){
             super.做餐();
             做西餐
         }
     }
     

     public class Person {
         String name;
         int age;
         String address;
         Person(String name,int age,String address){
             this.name = name;
             this.age = age;
             this.address = address;
         }
     
         void eat(){
             System.out.println(name+"正在吃饭...");
         }
         void sleep(){
             System.out.println(name+"正在睡觉...");
         }
         void sayHi(){
             System.out.println("大家好，我叫"+name+"，今年"+age+"岁了，家住"+address);
         }
     }
     
     public class Student extends Person{
         String className;
         String stuId;
         Student(String name,int age,String address,String className,String stuId){
             super(name,age,address); //传递的是name/age/address的值
             this.className = className;
             this.stuId = stuId;
         }
     
         void study(){
             System.out.println(name+"正在学习...");
         }
         
         void sayHi(){
             System.out.println("大家好，我叫"+name+"，今年"+age+"岁了，家住"+address+"，所在班级为:"+className+"，学号为："+stuId);
         }
     }
     
     public class Teacher extends Person{
         double salary;
         Teacher(String name,int age,String address,double salary){
             super(name,age,address);
             this.salary = salary;
         }
     
         void teach(){
             System.out.println(name+"正在讲课...");
         }
         
         void sayHi(){
             System.out.println("大家好，我叫"+name+"，今年"+age+"岁了，家住"+address+"，工资为:"+salary);
         }
     }
     
     public class Doctor extends Person {
         String title;
         Doctor(String name,int age,String address,String title){
             super(name,age,address);
             this.title = title;
         }
         void cut(){
             System.out.println(name+"正在做手术...");
         }
     }
     
     public class ExtendsTest {
         public static void main(String[] args) {
             Student zs = new Student("张三",25,"廊坊","jsd2302","001");
             zs.eat();
             zs.sleep();
             zs.sayHi();
             zs.study();
     
             Teacher ls = new Teacher("李四",35,"佳木斯",6000.0);
             ls.eat();
             ls.sleep();
             ls.sayHi();
             ls.teach();
     
             Doctor ww = new Doctor("王五",46,"山东","主任医师");
             ww.eat();
             ww.sleep();
             ww.sayHi();
             ww.cut();
         }
     }
     

2. 综合练习：

   public class Animal {
       String name;
       int age;
       String color;
       Animal(String name,int age,String color){
           this.name = name;
           this.age = age;
           this.color = color;
       }
       void drink(){
           System.out.println(color+"色的"+age+"岁的"+name+"正在喝水...");
       }
       void eat(){ //---------------明天继续改造
           System.out.println(color+"色的"+age+"岁的"+name+"正在吃饭...");
       }
   }
   
   public class Dog extends Animal {
       Dog(String name,int age,String color){
           super(name,age,color);
       }
       void lookHome(){
           System.out.println(color+"色的"+age+"岁的狗狗"+name+"正在看家...");
       }
       void eat(){
           System.out.println(color+"色的"+age+"岁的狗狗"+name+"正在吃肯头...");
       }
   }
   
   public class Chick extends Animal {
       Chick(String name,int age,String color){
           super(name,age,color);
       }
       void layEggs(){
           System.out.println(color+"色的"+age+"岁的小鸡"+name+"正在下蛋...");
       }
       void eat(){
           System.out.println(color+"色的"+age+"岁的小鸡"+name+"正在吃小米...");
       }
   }
   
   public class Fish extends Animal {
       Fish(String name,int age,String color){
           super(name,age,color);
       }
       void eat(){
           System.out.println(color+"色的"+age+"岁的小鱼"+name+"正在吃小虾...");
       }
   }
   
   public class Test {
       public static void main(String[] args) {
           Dog dog1 = new Dog("小黑",2,"黑");
           dog1.eat();
           dog1.drink();
           dog1.lookHome();
   
           Dog dog2 = new Dog("小白",1,"白");
           dog2.eat();
           dog2.drink();
           dog2.lookHome();
   
           Dog dog3 = new Dog("小强",2,"黑白");
           dog3.eat();
           dog3.drink();
           dog3.lookHome();
   
           Chick chick = new Chick("花花",1,"棕");
           chick.eat();
           chick.drink();
           chick.layEggs();
   
           Fish fish = new Fish("金金",2,"金");
           fish.eat();
           fish.drink();
       }
   }