1. Collection vs Collections
首先，“Collection”和“Collections”是兩個不同的概念。你可以從下面的層次關係圖中看到，”Collection”是集合層次的頂層接口，而”Collections”是提供了操作集合類型的靜態方法的類。
2. 集合類層次關係圖
下圖是集合類的層次關係圖
3. Map的類層次結構關係圖
下圖是Map的類層次結構關係圖
4. 集合類總結
5. 代碼示例
下面是一個簡單的集合的例子：
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List a1 = new
ArrayList(); a1.add("Program");
a1.add("Creek");
a1.add("Java");
a1.add("Java");
System.out.println("ArrayList Elements");
System.out.print("\t"
+ a1 + "\n");
List l1 = new
LinkedList(); l1.add("Program");
l1.add("Creek");
l1.add("Java");
l1.add("Java");
System.out.println("LinkedList Elements");
System.out.print("\t"
+ l1 + "\n");
Set s1 =
new HashSet();
// or new TreeSet() will order the elements; s1.add("Program");
s1.add("Creek");
s1.add("Java");
s1.add("Java");
s1.add("tutorial");
System.out.println("Set Elements");
System.out.print("\t"
+ s1 + "\n");
Map m1 =
new HashMap();
// or new TreeMap() will order based on keys m1.put("Windows",
"2000");
m1.put("Windows",
"XP"); m1.put("Language",
"Java");
m1.put("Website",
"programcreek.com");
System.out.println("Map Elements");
System.out.print("\t"
+ m1); |
輸出:
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ArrayList Elements
[Program, Creek, Java, Java]
LinkedList Elements
[Program, Creek, Java, Java]
Set Elements
[tutorial, Creek, Program, Java]
Map Elements
{Windows=XP, Website=programcreek.com, Language=Java} |
