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Java语言中,Set接口有3种通用实现:HashSet
, TreeSet,LinkedHashSet。
TreeSet是一种能够对内部元素进行排序的集合,它使用红黑树来存储内部元素,基于元素的值进行排序,它比HashSet要慢。
TreeSet要求内部元素实现Comparable接口,因为它是根据元素的compareTo来排序的。下面是一个demo:
package Colloections; import java.util.LinkedList; import java.util.TreeSet; public class TreeSetDemo { public static void main(String[] args) { // TODO Auto-generated method stub TreeSet<Person> treeSet = new TreeSet<Person>(); treeSet.add(new Person("albert", 8)); treeSet.add(new Person("bob", 5)); treeSet.add(new Person("bob", 13)); for (Person person : treeSet) { System.out.printf(person.toString()); } } } class Person implements Comparable<Person>{ public String name; public int age; public Person(String n, int a){ name = n; age = a; } public String toString() { return String.format("Name is %s, Age is %d%n", name, age); } @Override public int compareTo(Person o) { // TODO Auto-generated method stub int nameComp = this.name.compareTo(o.name); return (nameComp != 0 ? nameComp : (this.age - o.age)); } }
程序输出为:
Name is albert, Age is 8
Name is bob, Age is 5
Name is bob, Age is 13
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原文地址:http://www.cnblogs.com/pzy4447/p/5024197.html