尚学堂

import java.util.*;public class TestMap {  public static void main(String args[]) {    Map m1 = new HashMap();     Map m2 = new TreeMap();    //m1.put("one",new Integer(1));<span style="white-space:pre"></span>//为什么一定要放进去Integer对象呢？这是因为Map接口规定，里面存放的必须是成对的对象，以便放在栈空间里    m1.put("one", 1);<span style="white-space:pre"></span>//但是在现在版本的JDK中可以这么写，这叫自动打包自动解包    //m1.put("two",new Integer(2));    m1.put("two", 2);    //m1.put("three",new Integer(3));    m1.put("three", 3);    //m2.put("A",new Integer(1));   m2.put("A", 1);    //m2.put("B",new Integer(2));    m2.put("B", 2);    System.out.println(m1.size());    System.out.println(m1.containsKey("one"));    System.out.println        //(m2.containsValue(new Integer(1)));        (m2.containsValue(1));    if(m1.containsKey("two")) {      //int i = ((Integer)m1.get("two")).intValue();      int i = (Integer)m1.get("two");      System.out.println(i);    }    Map m3 = new HashMap(m1);    m3.putAll(m2);    System.out.println(m3);  }}