map的使用方法

package cn.stat.p8.map.demo;

import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

public class MapDemo2 {

    public static void main(String[] args) {
        Map<Integer,String> mapset=new HashMap<Integer,String>();
        method_2(mapset);
    }

    private static void method(Map<Integer, String> mapset) {
        mapset.put(8,"list");
        mapset.put(9,"list6");
        mapset.put(3,"list2");
        mapset.put(6,"list7");
        mapset.put(1,"list9");

        Set<Map.Entry<Integer,String>> ks=mapset.entrySet();
        Iterator<Map.Entry<Integer,String>> it=ks.iterator();
        while(it.hasNext())
        {
            Map.Entry<Integer,String>  me=it.next();

            Integer  key=me.getKey();
            String value=me.getValue();

            System.out.println(value+"  "+key);
        }
    }
    public static void method_2(Map<Integer, String> mapset) {
        mapset.put(8,"list");
        mapset.put(9,"list6");
        mapset.put(3,"list2");
        mapset.put(6,"list7");
        mapset.put(1,"list9");
        Collection<String> values=mapset.values();
        Iterator<String> it2=values.iterator();
        while(it2.hasNext())
        {
            System.out.println(it2.next());
        }
    }

}

treemap使用

package cn.stat.p7.map.demo;

import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;

public class MapDemo {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
     Map<Integer,String> map=new TreeMap<Integer,String>();
     method(map);
    }
    public static void method(Map<Integer,String> map)
    {
        //添加
        System.out.println(map.put(8,"wangcai"));
        System.out.println(map.put(8,"xiaoxiao"));
        map.put(2, "lili");
        map.put(9, "niuniu");

        System.out.println(map);

        //删除
        System.out.println(map.remove(2));

        System.out.println(map);

        //判断
        System.out.println("containskey:"+map.containsKey(8));
        System.out.println("containsvalues:"+map.containsValue("222"));

        //获取
        System.out.println(map.get(8));//不存在返回null
    }

}