JAVA-常用集合类型转换例子（基础必备）-白红宇

JAVA-常用集合类型转换例子（基础必备）

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发布时间：2019-06-14

本文共 2825 字，大约阅读时间需要 9 分钟。

package com.net.xinfang.reflect;import java.util.ArrayList;import java.util.Arrays;import java.util.HashMap;import java.util.HashSet;import java.util.List;import java.util.Map;import java.util.Set;/*** * Array、Set、List、Map相互转换 * @author xinfang * */public class ConvertorTest {	/**	 * @param args	 */	public static void main(String[] args) {		testList2Array();//List-Array		testArray2List();//Array-List		testSet2List();//Set-List		testList2Set();//List-Set		testSet2Array();//Set-Array		testArray2Set();//Array-Set		testMap2Set();//Map-Set		testMap2List();//Map-List	}	private static void testMap2List() {		Map
    
      map = new HashMap
     
      ();		map.put("A", "ABC");		map.put("K", "KK");		map.put("L", "LV");		// 将Map Key 转化为List		List
      
        mapKeyList = new ArrayList
       
        (map.keySet());		System.out.println("mapKeyList:" + mapKeyList);		// 将Map Key 转化为List		List
        
          mapValuesList = new ArrayList
         
          (map.values()); System.out.println("mapValuesList:" + mapValuesList); } private static void testMap2Set() { Map
          
            map = new HashMap
           
            (); map.put("A", "ABC"); map.put("K", "KK"); map.put("L", "LV"); // 将Map 的键转化为Set Set
            
              mapKeySet = map.keySet(); System.out.println("mapKeySet:" + mapKeySet); // 将Map 的值转化为Set Set
             
               mapValuesSet = new HashSet
              
               (map.values()); System.out.println("mapValuesSet:" + mapValuesSet); } private static void testArray2Set() { String[] arr = { "AA", "BB", "DD", "CC", "BB" }; // 数组-->Set Set
               
                 set = new HashSet
                
                 (Arrays.asList(arr)); System.out.println(set); } private static void testSet2Array() { Set
                 
                   set = new HashSet
                  
                   (); set.add("AA"); set.add("BB"); set.add("CC"); String[] arr = new String[set.size()]; // Set-->数组 set.toArray(arr); System.out.println(Arrays.toString(arr)); } private static void testList2Set() { List
                   
                     list = new ArrayList
                    
                     (); list.add("ABC"); list.add("EFG"); list.add("LMN"); list.add("LMN"); // List-->Set Set
                     
                       listSet = new HashSet
                      
                       (list); System.out.println(listSet); } private static void testSet2List() { Set
                       
                         set = new HashSet
                        
                         (); set.add("AA"); set.add("BB"); set.add("CC"); // Set --> List List
                         
                           setList = new ArrayList
                          
                           (set); System.out.println(setList); } private static void testList2Array() { // List-->数组 List
                           
                             list = new ArrayList
                            
                             (); list.add("AA"); list.add("BB"); list.add("CC"); Object[] objects = list.toArray();// 返回Object数组 System.out.println("objects:" + Arrays.toString(objects)); String[] arr = new String[list.size()]; list.toArray(arr);// 将转化后的数组放入已经创建好的对象中 System.out.println("strings1:" + Arrays.toString(arr)); } private static void testArray2List() { // 数组-->List String[] ss = { "JJ", "KK" }; List
                             
                               list1 = Arrays.asList(ss); List
                              
                                list2 = Arrays.asList("AAA", "BBB"); System.out.println(list1); System.out.println(list2); }}