1 package com.bytezreo.interfacetest; 2 3 /** 4 * 5 * @Description 接口:比较对象的大小 6 * @author Bytezero·zhenglei! Email:420498246@qq.com 7 * @version 8 * @date 下午9:07:52 9 * @ 10 * 11 */ 12 13 public class ComparableCircleTest { 14 15 public static void main(String[] args) { 16 17 ComparableCircle c1 = new ComparableCircle(3.4); 18 ComparableCircle c2 = new ComparableCircle(3.6); 19 20 int compareValue = c1.compareTo(c2); 21 if(compareValue > 0) { 22 System.out.println("c1对象大"); 23 }else if(compareValue < 0) { 24 System.out.println("c2对象大"); 25 }else { 26 System.out.println("c1与c2一样大"); 27 } 28 29 30 31 32 } 33 }
1 package com.bytezreo.interfacetest; 2 3 4 public class ComparableCircle extends Circle implements CompareObject { 5 6 7 public ComparableCircle(double radius) { 8 super(radius); 9 } 10 @Override 11 public int compareTo(Object o) { 12 if(this == o) { 13 return 0; 14 } 15 16 if(o instanceof ComparableCircle ) { 17 ComparableCircle c = (ComparableCircle)o; 18 19 //错误的 20 // return (int) (this.getRadius() - c.getRadius()); 21 22 //正确的 23 if(this.getRadius() > c.getRadius()) { 24 return 1; 25 }else if(this.getRadius() < c.getRadius()) { 26 return -1; 27 }else { 28 return 0; 29 } 30 }else { 31 return 0; 32 //throw new RuntimeException("传入的数据类型不匹配"); 33 34 } 35 36 37 } 38 39 40 }
1 package com.bytezreo.interfacetest; 2 3 public class Circle { 4 5 private double radius; 6 7 public double getRadius() { 8 return radius; 9 } 10 11 public void setRadius(double radius) { 12 this.radius = radius; 13 } 14 15 public Circle() { 16 super(); 17 } 18 19 public Circle(double radius) { 20 super(); 21 this.radius = radius; 22 } 23 24 25 26 }
1 package com.bytezreo.interfacetest; 2 3 public interface CompareObject { 4 5 //若返回值是 0代表相等; 若为正数,代表当前对象大; 负数代表当前对象小 6 public int compareTo(Object o); 7 8 }