Set

package com.cavaness.quartzbook.chapter3;import java.util.Collection;import java.util.HashSet;public class Point {private int x;private int y;public Point(int x, int y) {super();this.x = x;this.y = y;}public int getX() {return x;}public void setX(int x) {this.x = x;}public int getY() {return y;}public void setY(int y) {this.y = y;}@Overridepublic String toString() {return "Point [x=" + x + ", y=" + y + "]";}public static void main(String[] args) {Point point = new Point(1, 2);Point point2 = new Point(1, 2);Point point3 = new Point(3, 4);Collection<Point> points = new HashSet<Point>();points.add(point);points.add(point2);points.add(point3);points.add(point2);System.out.println(points.size()); // 3 List 若是equals为true且hashcode为true,则认为是同一元素,不可重复放置for (Point point4 : points) {System.out.println(point4);}}}