Java集合框架的接口和類層次關系結構圖

Collection和Collections的區別

首先要說的是，"Collection" 和 "Collections"是兩個不同的概念；

如下圖所示，"Collection"是集合類（Collection）的頂級接口，然而”Collections“是一個提供了一系列靜態方法的集合工具類；

Collection的類層次結構圖

Map的類層次結構圖

總結

代碼示例

package simplejava;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;

public class Q7 {

    public static void main(String[] args) {
        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);
    }

}

結果打印：

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}

譯文鏈接：http://www.programcreek.com/2009/02/the-interface-and-class-hierarchy-for-collections/