45 lines
1.1 KiB
Java
45 lines
1.1 KiB
Java
package ch04;
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abstract class Animal{
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public abstract void eat(); //只有方法名，而没有方法体
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}
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class Dog extends Animal{
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private String name;
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public void setName(String name){
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this.name=name;
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}
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public String getName(){
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return name;
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}
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public void eat(){
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System.out.println("小狗啃骨头啦");
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}
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}
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class Bird extends Animal{
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public void fly( ){
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System.out.println("小鸟飞呀飞呀");
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}
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public void eat( ){
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System.out.println("小鸟吃虫子啦");
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}
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}
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public class BackAnimal{
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public static void main( String args[ ] ){
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Animal a1=new Animal(); //1.该行代码可不可以执行？为什么？
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Animal an = new Dog( );
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an.eat( ); //2.该行代码输出什么？
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an=new Bird();
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an.eat(); //3.该行代码输出什么？
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Animal x1=new Dog();
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Animal x2=new Bird();
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print(x1); //4.以下2行代码输出什么？为什么？
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print(x2);
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}
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public static void print(Animal a){
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a.eat();
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}
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}
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