HashMap，LinkedHashMap，TreeMap读取大量数据效率的比较

  @Test
  public void test() {
    Integer count =1000000;
    Random random =new Random();
    Map<String, String> map = new HashMap<String, String>();
    for (int i = 0; i < count; i++) {
      map.put(i+"", i+"");
    }
    long time1 = System.currentTimeMillis();
    for (int i = 0; i < count; i++) {
      map.get((random.nextInt(count)+1)+"");
    }
    long time2 = System.currentTimeMillis();
    System.out.println("HashMap time:" + (time2 - time1));
    Map<String, String> linkedMap = new LinkedHashMap<String, String>();
    for (int i = 0; i < count; i++) {
      linkedMap.put(i+"", i+"");
    }
    time1 = System.currentTimeMillis();
    for (int i = 0; i < count; i++) {
       linkedMap.get((random.nextInt(count)+1)+"");
    }
    time2 = System.currentTimeMillis();
    System.out.println("LinkedHashMap time:" + (time2 - time1));
    Map<String, String> treeMap = new TreeMap<String, String>();
    for (int i = 0; i < count; i++) {
      treeMap.put(i+"", i+"");
    }
    time1 = System.currentTimeMillis();
    for (int i = 0; i < count; i++) {
      treeMap.get((random.nextInt(count)+1)+"");
    }
    time2 = System.currentTimeMillis();
    System.out.println("TreeMap time:" +  (time2 - time1));
  }

  @Test
  public void test2() {
    Integer count =1000000;
    Random random =new Random();
    Map<String, String> map = new HashMap<String, String>();
    for (int i = 0; i < count; i++) {
      map.put(i+"", i+"");
    }
    long time1 = System.currentTimeMillis();
    for (int i = 0; i < count; i++) {
      map.get(i+"");
    }
    long time2 = System.currentTimeMillis();
    System.out.println("HashMap time:" + (time2 - time1));
    Map<String, String> linkedMap = new LinkedHashMap<String, String>();
    for (int i = 0; i < count; i++) {
      linkedMap.put(i+"", i+"");
    }
    time1 = System.currentTimeMillis();
    for (int i = 0; i < count; i++) {
       linkedMap.get(i+"");
    }
    time2 = System.currentTimeMillis();
    System.out.println("LinkedHashMap time:" + (time2 - time1));
    Map<String, String> treeMap = new TreeMap<String, String>();
    for (int i = 0; i < count; i++) {
      treeMap.put(i+"", i+"");
    }
    time1 = System.currentTimeMillis();
    for (int i = 0; i < count; i++) {
      treeMap.get(i+"");
    }
    time2 = System.currentTimeMillis();
    System.out.println("TreeMap time:" +  (time2 - time1));
  }