content: package com.alibaba.druid.pool;
  
  import java.util.*;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentLinkedQueue;
  import java.util.concurrent.ConcurrentSkipListMap;
  import java.util.concurrent.CopyOnWriteArrayList;
  import java.util.concurrent.CopyOnWriteArraySet;
  
  public class MemTest {
      HashMap m = new HashMap();
      HashMap m1 = new HashMap(1);
      ConcurrentHashMap cm = new ConcurrentHashMap();
      ConcurrentHashMap cm1 = new ConcurrentHashMap(1, 0.75f, 1);
      ConcurrentSkipListMap csm = new ConcurrentSkipListMap();
      Hashtable ht = new Hashtable();
      Properties p = new Properties();
      TreeMap t = new TreeMap();
      LinkedHashMap l = new LinkedHashMap();
  
      TreeSet ts = new TreeSet();
      HashSet hs = new HashSet();
      LinkedHashSet lhs = new LinkedHashSet();
  
      ArrayList list = new ArrayList();
      ArrayList list1 = new ArrayList(1);
  
      CopyOnWriteArrayList cpl = new CopyOnWriteArrayList();
      CopyOnWriteArraySet cps = new CopyOnWriteArraySet();
      Vector v = new Vector();
      LinkedList ll = new LinkedList();
      Stack stack = new Stack();
      PriorityQueue pq = new PriorityQueue();
      ConcurrentLinkedQueue clq = new ConcurrentLinkedQueue();
  
      public static void main(String[] args) throws Exception {
          MemTest o = new MemTest();
  
          Thread.sleep(1000 * 1000);
  
          System.out.println(o);
      }
  }
  