32、TreeSet简介

package com.monkey1024.set;

import java.util.Comparator;

import com.monkey1024.bean.Person;

public class CompareByNameLength implements Comparator<Person> {

    @Override
    public int compare(Person p1, Person p2) {
        //根据name长度进行排序
        int num = p1.getName().length() - p2.getName().length();
        if(num == 0){
            num = p1.getName().compareTo(p2.getName());
            if(num == 0){
                num = p1.getAge() - p2.getAge();
            }
        }
        return num;
    }

}

package com.monkey1024.set;

import java.util.TreeSet;

import com.monkey1024.bean.Person;

/**
 * TreeSet可以对元素进行排序
 * 使用TreeSet根据name长度进行排序
 *
 */
public class TreeSetTest03 {

    public static void main(String[] args) {
        TreeSet<Person> ts = new TreeSet<>(new CompareByNameLength());
        ts.add(new Person("tony", 23));
        ts.add(new Person("jordan", 20));
        ts.add(new Person("tim", 22));
        ts.add(new Person("james", 24));
        ts.add(new Person("an", 21));


        System.out.println(ts);
    }

}

package com.monkey1024.set.exercise;

import java.util.Comparator;
import java.util.Scanner;
import java.util.TreeSet;

/**
 * 问题：将一个字符串中的字符按照字典顺序进行排序，要保留重复的字符。例如输入：java，打印aajv
 * 分析：向输入的字符串转换为字符数组，然后向TreeSet中添加字符
 */
public class Exercise03 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);            //创建键盘录入对象
        System.out.println("请输入一行字符串:");
        String line = sc.nextLine();                    //将键盘录入的字符串存储在line中
        char[] arr = line.toCharArray();                //将字符串转换成字符数组
        TreeSet<Character> ts = new TreeSet<>(new Comparator<Character>() {

            @Override
            public int compare(Character c1, Character c2) {
                int num = c1.compareTo(c2);
                //保存重复数据
                return num == 0 ? 1 : num;
            }
        });

        for(char c : arr) {
            ts.add(c);
        }

        for(Character ch : ts) {
            System.out.print(ch);
        }
    }

}