java基础知识——类的继承

1.在子类中通过super调用父类的方法，并将该调用嵌入复写该方法的过程中

package learning;

class Super {
     String nameString;
     int age;
     public Super(String name, int age) {
        this.nameString = name;
        this.age = age;
    } 
     public void talk(){
         System.out.print("姓名：" + nameString + "\t\t" + "年龄:" + age);
     }
}
class Student extends Super{
    String school;
    public Student(){
        super("张三", 25 );
    }
    //The method of Rewrite
    public void talk(){
        super.talk();
        System.out.println("\t\t" + "学校:" + school);
    }
}
/**
 * The method of super()
 * @author juefan
 */
public class Test1{
    public static void main(String[] args){
        Student student = new Student();
        student.school = "华附";
        student.talk();
    }
}

2.了解接口与接口实现的简单应用例子

package learning;

interface Usb{
    public void start();
    public void stop();
}
class Mp3 implements Usb{
    public void start(){
        System.out.println("Mp3 start... ");
    }
    public void stop(){
        System.out.println("Mp3 Stop...");
    }
}
class CD implements Usb{
    public void start(){
        System.out.println("CD start...");
    }
    public void stop(){
        System.out.println("CD stop...");
    }
}
class Computer{
    public void work(Usb usb){
        usb.start();
        usb.stop();
    }
}
/**
 * 以Usb类为接口类，Mp3跟CD都是Usb类的实现
 * Computer类会有Usb接口作为参数，调用Usb接口的实现输出
 * @author juefan
 *
 */
public class TestInterface {
    public static void main(String[] args){
        Computer computer = new Computer();
        computer.work(new Mp3());
        computer.work(new CD());
    }
}

可以看到Computer类中的work(Usb )方法是以Usb接口作为参数的

而Mp3跟CD都是Usb的接口的实现，这样就可以调用Mp3跟CD类中复写Usb接口中抽象方法的具体实现了，一个方法多种用处