2016/6/7学习记录

Posted 2020-07-22

1.接口和抽象类的区别，详情见转载的几篇文章，分析的非常透彻

http://blog.csdn.net/xw13106209/article/details/6923556

几个小例子，有助于理解。

package Demo;

import java.util.Arrays;

public class Test3 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        C[] s = { new C(1, 2), new C(2, 5), new C(3, 3), new C(1, 6) };
        Arrays.sort(s);
        for (C i : s)
            System.out.println(i.toString());
    }

}

class rectangle {
    private double width;
    private double height;

    public rectangle(double width, double height) {
        // TODO Auto-generated constructor stub
        this.width = width;
        this.height = height;
    }

    public double getArea() {
        return width * height;
    }

    public String toString() {
        return "width is " + width + "height is " + height;
    }
}

class C extends rectangle implements Comparable<rectangle> {
    public C(double width, double height) {
        super(width, height);
    }

    @Override
    public int compareTo(rectangle c) {
        if (getArea() > c.getArea())
            return 1;
        else if (getArea() == c.getArea())
            return 0;
        else
            return -1;
    }

    @Override
    public String toString() {
        return super.toString() + "the area is " + getArea();
    }
}

上面的例子是关于comparable接口的，对类C实现继承rectangle和Comparable接口，使得C类的对象可以进行比较，可以排序输出。

package Demo;

public class SSSS {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
    Student i = new Student("fan");
    i.sing();
    i.sleep();
    Painter j =(Painter)i;
    j.dance();
    j.paint();
    }

}

interface Singer{
    public void sing();
    public void sleep();
}
interface Painter{
    public void paint();
    public void dance();
}

class Student implements Singer,Painter{
    private String name ;
    public Student(String name) {
        this.name = name;
        // TODO Auto-generated constructor stub
    }
    public void study(){
    }
    public String getName(){
        return name;
    }
    public void sing(){
        System.out.println("I am sing!!!");
    }
    public void sleep(){
        System.out.println("I am sleeping");
    }
    public void paint(){
        
    }
    public void dance(){}

}