package cn.itcast_06;

import java.util.TreeSet;

import cn.itcast_06.Student;

/*
 * 需求:請按照姓名的長度排序
 */
public class TreeSetDemo {
	public static void main(String[] args) {
		// 建立集合物件
		TreeSet<Student> ts = new TreeSet<Student>();

		// 建立學生物件
		Student s1 = new Student("linqingxia", 27);
		Student s2 = new Student("zhangguorong", 29);
		Student s3 = new Student("wanglihong", 23);
		Student s4 = new Student("linqingxia", 27);
		Student s5 = new Student("liushishi", 22);
		Student s6 = new Student("wuqilong", 40);
		Student s7 = new Student("fengqingyang", 22);
		Student s8 = new Student("linqingxia", 29);

		// 新增元素
		ts.add(s1);
		ts.add(s2);
		ts.add(s3);
		ts.add(s4);
		ts.add(s5);
		ts.add(s6);
		ts.add(s7);
		ts.add(s8);

		// 遍歷
		for (Student s : ts) {
			System.out.println(s.getName() + "---" + s.getAge());
		}
	}
}
 

package cn.itcast_06;

/*
 * 如果一個類的元素要想能夠進行自然排序,就必須實現自然排序介面
 */
public class Student implements Comparable<Student> {
	private String name;
	private int age;

	public Student() {
		super();
		// TODO Auto-generated constructor stub
	}

	public Student(String name, int age) {
		super();
		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;
	}

	public int compareTo(Student s) {
		// 主要條件
		int num = this.name.length() - s.name.length();
		// 姓名的長度相同,不代表姓名的內容相同
		int num2 = num == 0 ? this.name.compareTo(s.name) : num;
		// 姓名的長度和內容相同,不代表年齡相同,所以還得繼續判斷年齡
		int num3 = num2 == 0 ? (this.age - s.age) : num2;
		return num3;
	}
}