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  • JAVA中list,set,map与数组之间的转换详解

    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);
    
    
    
        }
    }
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  • 原文地址:https://www.cnblogs.com/huzi007/p/5993949.html
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