获取map中的一个value值以及遍历map获得map里所有key、value的值

前言：

1.声明一个map: Map map = new HashMap();

2.向map中放值,注意：map是key-value的形式存放的.如:

map.put(”sa”,”dd”);

3.从map中取值:String str = map.get(”sa”).toString();结果是:str = ”dd”;

4.遍历一个map，从中取得key 和value

Map map = new HashMap() ;

Iterator it = map.entrySet().iterator() ;

while (it.hasNext())

{

Map.Entry entry = (Map.Entry) it.next() ;

Object key = entry.getKey() ;

Object value = entry.getValue() ;

}

Java代码如下：

package Test01;

import java.util.HashMap;

import java.util.Iterator;

import java.util.Map;

public class Test03 {

public static void main(String[] args){

a();

b();

}

@SuppressWarnings(“unchecked”)

public static void a(){

@SuppressWarnings(“rawtypes”)

Map map = new HashMap();

map.put(“1”,“aa”);

map.put(“2”,“bb”);

map.put(“3”,“cc”);

map.put(“4”,“dd”);

map.put(“5”,“ee”);

map.put(“6”,“ff”);

map.put(“7”,“gg”);

String str = map.get(“5”).toString();

System.out.println(str);

}

@SuppressWarnings(“unchecked”)

public static void b(){

@SuppressWarnings(“rawtypes”)

Map map = new HashMap();

map.put(“1”,“aa”);

map.put(“2”,“bb”);

map.put(“3”,“cc”);

map.put(“4”,“dd”);

map.put(“5”,“ee”);

map.put(“6”,“ff”);

map.put(“7”,“gg”);

@SuppressWarnings(“rawtypes”)

Iterator it = map.entrySet().iterator() ;

while (it.hasNext())

{

@SuppressWarnings(“rawtypes”)

Map.Entry entry = (Map.Entry) it.next() ;

Object key = entry.getKey() ;

Object value = entry.getValue() ;

System.out.print(“[”+key+“、”);

System.out.print(value+“]”);

System.out.print(“,”);

}

}

}

代码运行后效果如下：

原文：http://www.cnblogs.com/henuyuxiang/p/3868176.html