几幅图让你认识Java集合

1.Collection 和 Collections

     首先Collection和Collections是两个完全不同的范畴。正如下图，Collection是所有集合的root接口,而Collections仅仅是一个工具类，它提供了很多静态的工具方法来操作一个集合。

2. 集合的继承树

3.Map的继承树

4.总结

5.示例代码

Code:

List<String> a1 = new ArrayList<String>();
a1.add("Program");
a1.add("Creek");
a1.add("Java");
a1.add("Java");System.out.println("ArrayList Elements");System.out.print("\t" + a1 + "\n");

List<String> l1 = new LinkedList<String>();
l1.add("Program");
l1.add("Creek");
l1.add("Java");
l1.add("Java");System.out.println("LinkedList Elements");System.out.print("\t" + l1 + "\n");

Set<String> s1 = new HashSet<String>(); // 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<String, String> m1 = new HashMap<String, String>(); // 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);

Output:

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}

关于Java集合的详细介绍请阅读【Java集合概览】