package test;

import java.util.*;

/**

 * Created by ming

 */

public class Test {

    public static void main(String[] args) {

        Set<Long> longSet=new HashSet<>();

        longSet.add(1L);

        longSet.add(2L);

        List<Long> longList=new ArrayList<>();

        longList.addAll(longSet);//list转set

        for(Long t : longList){

            System.out.println(t);

        }

        Set<Long> set2=new HashSet<>();

        set2.addAll(longList);//list转set

        for(Long s : set2){

            System.out.println(s);

        }

        Map<Long,Long> map=new HashMap<>();//list转map

        for(Long t : longList){

            map.put(t,t);

        }

        for(Long s : set2){//set转map

            System.out.println(s);

        }

        Collection<Long> collections= map.values();

        for (Long t : collections){

            System.out.println("map转集合"+t);

        }

        Long longs[]={2L,3L,4L};//定义一个数组

        List<Long> longList1 = Arrays.asList(longs);//数组转集合

        for(Long t : longList1){

            System.out.println("数组转集合"+t);

        }

       Long [] newLongs= longList1.toArray(new Long []{});

        System.out.println("集合转数组的方法:"+newLongs.length);

    }

}