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：