Array、List、Set、Map相互之间的转换 

  1 import java.util.ArrayList;
  2 import java.util.Arrays;
  3 import java.util.HashMap;
  4 import java.util.HashSet;
  5 import java.util.List;
  6 import java.util.Map;
  7 import java.util.Set;
  8 
  9 public class ConvertorTest {
 10 
 11     public static void main(String[] args) {
 12         testList2Array();
 13         testArray2List();
 14         
 15         testSet2List();
 16         testList2Set();
 17         
 18         testSet2Array();
 19         testArray2Set();
 20         
 21         testMap2Set();
 22         testMap2List();
 23     }
 24 
 25     /**
 26      * map-->list
 27      */
 28     private static void testMap2List() {
 29         Map<String, String> map = new HashMap<String, String>();
 30         map.put("A", "ABC");
 31         map.put("K", "KK@@");
 32         map.put("K", "34567");//覆盖
 33         map.put("L", "LV");
 34         
 35         List<String> mapKeyList = new ArrayList<String>(map.keySet());
 36         System.out.println("map-->list,key:" + mapKeyList);
 37         
 38         List<String> mapValueList = new ArrayList<String>(map.values());
 39         System.out.println("map-->list,value:" + mapValueList);
 40     }
 41 
 42     /**
 43      * Map-->Set
 44      */
 45     private static void testMap2Set() {
 46         Map<String, String> map = new HashMap<String, String>();
 47         map.put("A", "ABC");
 48         map.put("K", "KK23");
 49         map.put("K", "KK");//覆盖
 50         map.put("L", "LV");
 51         
 52         Set<String> mapKeySet = new HashSet<String>(map.keySet());
 53         System.out.println("Map-->Set,keySet" + mapKeySet);
 54         
 55         Set<String> mapValueSet = new HashSet<String>(map.values());
 56         System.out.println("Map-->Set,valueSet" + mapValueSet);
 57         
 58     }
 59 
 60     /**
 61      * 数组-->Set
 62      */
 63     private static void testArray2Set() {
 64         String[] arr = {"AA", "BB", "DD", "CC", "BB"};
 65         Set<String> set = new HashSet<String>(Arrays.asList(arr));
 66         System.out.println("数组-->Set:" + set);
 67     }
 68 
 69     /**
 70      * set-->数组
 71      */
 72     private static void testSet2Array() {
 73         Set<String> set = new HashSet<String>();
 74         set.add("AA");
 75         set.add("AA");
 76         set.add("AA");
 77         set.add("BB");
 78         set.add("CC");
 79         
 80         String[] arr = new String[set.size()];
 81         
 82         set.toArray(arr);
 83         System.out.println("set-->数组：" + Arrays.toString(arr));
 84     }
 85 
 86     /**
 87      * List-->Set
 88      */
 89     private static void testList2Set() {
 90         List<String> list = new ArrayList<String>();
 91         list.add("ABC");
 92         list.add("EFG");
 93         list.add("LMN");
 94         list.add("LMN");
 95         
 96         Set<String> listSet = new HashSet<String>(list);
 97         System.out.println("List-->Set：" + listSet);
 98     }
 99 
100     /**
101      * Set-->List
102      */
103     private static void testSet2List() {
104         Set<String> set = new HashSet<>();
105         set.add("AA");
106         set.add("BB");
107         set.add("BB");//去重
108         set.add("CC");
109         
110         List<String> setList = new ArrayList<String>(set);
111         System.out.println("Set-->List：" + setList);
112     }
113 
114     /**
115      * 数组-->list
116      */
117     private static void testArray2List() {
118         String[] ss = {"JJJ","KKKK"};
119         List<String> list1 = Arrays.asList(ss);
120         List<String> list2 = Arrays.asList("AAA", "BBB");
121         System.out.println("数组-->list:" + list1);
122         System.out.println("数组-->list:" + list2);
123     }
124 
125     /**
126      * List-->数组
127      */
128     private static void testList2Array() {
129         List<String> list = new ArrayList<String>();
130         list.add("AAA");
131         list.add("AAAA");
132         list.add("BBB");
133         list.add("CCC");
134         Object[] objects = list.toArray();
135         System.out.println("List-->数组:" + Arrays.toString(objects));
136         
137         String[] arr = new String[list.size()];
138         list.toArray(arr);
139         System.out.println("String:" + Arrays.toString(arr));
140     }
141 }

Java集合（Array，List，Set，Map之间转换的图形）

 

 

posted @ 2017-05-06 12:53  HotSpot  Views(2)  Comments(0)    收藏  举报