hashmap

package pk;

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

public class hashmap {

/**
* @param args
*/
public  static void  showelement(Collection c)
{
Iterator it=c.iterator();
while(it.hasNext())
{
System.out.println(it.next());

}


}
public static void main(String[] args) {
TreeMap mp=new TreeMap();
mp.put("1", "z454ang");
mp.put("2", "zha555ng");
mp.put("3", "zh663ang");
mp.put("4", "zha654ng");

System.out.println("ddddd"+mp.get("1"));

    //返回key
Set n=mp.keySet();
showelement(n);

//返回value
Collection c=mp.values();
showelement(c);


//返回键值对
Set s=mp.entrySet();
showelement(s);

//如何单独访问键或值
Iterator it=s.iterator();
while(it.hasNext())
{
Map.Entry me=(Map.Entry)it.next();
System.out.println(me.getKey()+"  "+me.getValue());

}

}

}
//map.Entry 返回一个对的关系，可以分别获得key,value