TreeSet根据一个字段排序

来源：互联网发布：袁姗姗知乎编辑：程序博客网时间：2024/06/01 07:23
TreeSet根据一个字段排序
package com.Set;import java.util.HashSet;import java.util.Iterator;import java.util.TreeSet;import javax.management.RuntimeErrorException;/** *  * @author 小明 * 往TreeSet集合中存储自定义对象学生;想按照学生的年龄进行排序 */class Student implements Comparable{//该接口强制比较性private String name;private int age;Student(String name,int age){this.name = name;this.age = age;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}@Overridepublic boolean equals(Object obj) {if(!(obj instanceof Student)){return false;}Student p = (Student) obj;System.out.println(this.name+"-equals--"+p.name);return this.name.equals(p.name) && this.age==p.age;}@Overridepublic int hashCode() {System.out.println(this.name+"...hashcode...");//return 60;return name.hashCode()+age;}@Overridepublic int compareTo(Object obj) {if(!(obj instanceof Student)){  throw new RuntimeException("不是学生");}Student s = (Student) obj;System.out.println(this.name +" comp.."+s.name);if(this.age >s.age){return 1;}if(this.age==s.age){return this.name.compareTo(s.name);}return -1;}}public class TreeSetTest {public static void main(String[] args) {TreeSet<Student> hs = new TreeSet<Student>();hs.add(new Student("zhangsan", 20));hs.add(new Student("lisi", 30));hs.add(new Student("lisi01", 40));hs.add(new Student("xiao", 50));hs.add(new Student("xiao003", 50));hs.add(new Student("xiao001", 50));Iterator<Student> iterator = hs.iterator();while(iterator.hasNext()){Student p = iterator.next();System.out.println(p.getName()+"   "+p.getAge());}}}
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