/javaDemo3/src/com/imooc/Dog.java

package com.imooc;  public class Dog extends Animal {     public void eat() {         System.out.println("年龄:"+age+ "狗可以吃东西" );     }     public Dog() {         System.out.println("Dog类执行了" );     } } 

/javaDemo3/src/com/imooc/InITail.java

package com.imooc;  public class Initail {      public static void main(String[] args) {         // TODO Auto-generated method stub         Dog dog = new Dog();         dog.age = 10;         dog.name = "aa";         dog.eat();     }  } 

对象的属性和构造方法

/javaDemo3/src/com/imooc/Animal.java

package com.imooc;  public class Animal {     public int age = 10;     public String name;     public void eat() {         System.out.println("年龄:"+age+ "动物可以吃东西" );     }     public Animal() {         age = 20;         System.out.println("Animal类执行了" );     } } 

/javaDemo3/src/com/imooc/Initail.java

package com.imooc;  public class Initail {      public static void main(String[] args) {         // TODO Auto-generated method stub         Animal animal = new Animal();          System.out.println("animal的age:" + animal.age );         Dog dog = new Dog();         dog.age = 10;         dog.name = "aa";         dog.eat();     }  }