Java集合框架的接口和类层次关系结构图

Collection和Collections的区别

首先要说的是，"Collection" 和 "Collections"是两个不同的概念；

如下图所示，"Collection"是集合类（Collection）的顶级接口，然而”Collections“是一个提供了一系列静态方法的集合工具类；

Collection的类层次结构图

Map的类层次结构图

总结

代码示例

 

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); } }

View Code

结果打印：

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}

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