Simple coding

Simple Life

2009年10月28日 #

HashMap,Hashtable,TreeMap,LinkedHashMap類的不同之處

HashMap	k=v的排列順序
Hashtable	key降序排列(從大到小數字排列)
TreeMap	key升序排列(從小到大數字排列)
LinkedHashMap	按照k=v放入的順序來排列

1 import java.util.Map;
2 public class JavaMapTest {
3         static public void main(String[] arg){
4                 Map<String, String> hm = new HashMap();
5                 Map<String, String> ht = new Hashtable();
6                 Map<String, String> tm = new TreeMap();
7                 Map<String, String> lhm = new LinkedHashMap();
8                 setData(hm);
9                 setData(ht);
10                 setData(tm);
11                 setData(lhm);
12                 System.out.println("HashMap: " + hm);
13                 System.out.println("Hashtable: " + ht);
14                 System.out.println("TreeMap: " + tm);
15                 System.out.println("LinkedHashMap: " + lhm);
16         }
17         static private void setData(Map<String,String> m){
18                 m.put("2", "200");
19                 m.put("3", "300");
20                 m.put("1", "100");
21                 m.put("5", "a");
22                 m.put("6", "b");
23                 m.put("4", "c");
24         }
25 }

執行結果如下：

HashMap: {3=300, 5=a, 2=200, 4=c, 6=b, 1=100}

Hashtable: {6=b, 5=a, 4=c, 3=300, 2=200, 1=100}

TreeMap: {1=100, 2=200, 3=300, 4=c, 5=a, 6=b}

LinkedHashMap: {2=200, 3=300, 1=100, 5=a, 6=b, 4=c}

posted @ 2009-11-18 09:31 stl0 閱讀(327) | 評論 (0) | 編輯收藏

HashMap子項目全部取得

1 HashMap<String,String> paramMap = new HashMap<String,String>();
2
3 String seqKey="";
4 String seqValue="";
5
6 paramMap.put(seqKey,seqValue);
7
8 Set<String> set = paramMap.keySet();
9 Iterator<String> iterator = set.iterator();
10
11 while (iterator.hasNext()) {
12 seqKey = iterator.next();
13 seqValue = paramMap.get(seqNo);
14 }

posted @ 2009-10-30 17:17 stl0 閱讀(106) | 評論 (0) | 編輯收藏