Collection  
├List  
│├LinkedList  
│├ArrayList  
│└Vector  
│　└Stack  
└Set 

import java.util.ArrayList; 
import java.util.Collections; 
import java.util.List; 
 
public class TestCollections { 
   
  public static void main(String args[]) { 
    //注意List是实现Collection接口的 
    List list = new ArrayList(); 
    double array[] = { 112, 111, 23, 456, 231 }; 
    for (int i = 0; i < array.length; i++) { 
      list.add(new Double(array[i])); 
    } 
    Collections.sort(list); 
    for (int i = 0; i < array.length; i++) { 
      System.out.println(list.get(i)); 
    } 
    // 结果：23 111 112 231 456 
  } 
}