1. Collection vs Collections
首先,“Collection”和“Collections”是两个不同的概念。你可以从下面的层次关系图中看到,”Collection”是集合层次的顶层接口,而”Collections”是提供了操作集合类型的静态方法的类。
2. 集合类层次关系图
下图是集合类的层次关系图
3. Map的类层次结构关系图
下图是Map的类层次结构关系图
4. 集合类总结
5. 代码示例
下面是一个简单的集合的例子:
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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); |
输出:
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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} |