Java 集合 List和Set的区别

import java.util.List;
import java.util.ArrayList;
import java.util.LinkedList;

public class ListExample {

 public static void main(String[] args) {
   List<String> al = new ArrayList<String>();
   al.add("Chaitanya");
   al.add("Rahul");
   al.add("Ajeet");
   System.out.println("ArrayList Elements: ");
   System.out.print(al);

   List<String> ll = new LinkedList<String>();
   ll.add("Kevin");
   ll.add("Peter");
   ll.add("Kate");
   System.out.println("\nLinkedList Elements: ");
   System.out.print(ll);
 }
}

ArrayList Elements: 
[Chaitanya, Rahul, Ajeet]
LinkedList Elements: 
[Kevin, Peter, Kate]

import java.util.Set;
import java.util.HashSet;
import java.util.TreeSet;

public class SetExample {

  public static void main(String args[]) { 
    int count[] = {11, 22, 33, 44, 55};
    Set<Integer> hset = new HashSet<Integer>();
    try{
      for(int i = 0; i<4; i++){
         hset.add(count[i]);
      }
      System.out.println(hset);

      TreeSet<Integer> treeset = new TreeSet<Integer>(hset);
      System.out.println("The sorted list is:");
      System.out.println(treeset);
    }
    catch(Exception e){
        e.printStackTrace();
    }
  }
}

[33, 22, 11, 44]
The sorted list is:
[11, 22, 33, 44]