集合例题

import java.util.Comparator;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Scanner;
import java.util.TreeSet;
public class pidsk {
	public static void main(String []args){
		System.out.println("输入字符");
		Scanner aScanner=new Scanner(System.in);
		String a=aScanner.next();
		TreeSet<String> liString=new TreeSet<>(new myu());
		
		//第一题
//		HashSet<Character> aHashSet=new HashSet<>();
//		for(int i=0;i<a.length();i++){
//			aHashSet.add(a.charAt(i));
//		}
//		System.out.println(aHashSet);
		System.out.println("++++++++++++++++++++");
		ArrayList<String> list = new ArrayList<>();
		ArrayList<String> blist = new ArrayList<>();
		list.add("ccc");
		list.add("ccc");
		list.add("aaa");
		list.add("aaa");
		list.add("bbb");
		list.add("ddd");
		list.add("ddd");
		TreeSet<String> liStrings=new TreeSet<>(new myu());
		//套入字典排序
		for (int i = 0; i < list.size(); i++) {
			liStrings.add(list.get(i));
			
		}
		//增加重复的字符
		//set迭代
		Iterator<String>  aIterator=liStrings.iterator();
		while(aIterator.hasNext()){
			String next = aIterator.next();//重点   
			for(int i=0;i<list.size();i++){
//				String next = aIterator.next();//重点   迭代放在里面会随循环下移，甚至超出去
			  if(list.get(i).equals(next)){
				  blist.add(list.get(i));
			  }
			}
		}
		System.out.println(blist);
	
	}
}
class myu implements Comparator<String>{

	@Override
	public int compare(String o1, String o2) {
		// TODO Auto-generated method stub
		if(o1.length()-o2.length()==0){
			return o1.compareTo(o2);//根据字典序比较并返回一个值
		}
		return o1.length()-o2.length();
	}
}