Two common ways through the collection

package sun;

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

/**
 * 遍历集合常见的两种方式
 * @author Administrator
 */
public class MapTest
{
	public static void main(String[] args)
	{
		Map<String,String> map = new HashMap<String,String>();
		
		map.put("a","aa");
		map.put("b","bb");
		map.put("c","cc");
		map.put("d","dd");
		
		//这是第一种遍历map的方式，先获得map的key，然后普通过key的值来得到value的值
		
		Set<String> set = map.keySet();
		
		for(Iterator<String> iter = set.iterator();iter.hasNext();)
		{
			String key = iter.next();
			String value = map.get(key);
			
			System.out.println(key + ":" + value);
		}
		
		System.out.println("----------------------------------------");
		
		//这是第二种遍历map的方式，一次性获得map的key和value值
		
		Set<Map.Entry<String,String>> set2 = map.entrySet();
		
		for(Iterator<Map.Entry<String,String>> iter2 = set2.iterator();iter2.hasNext();)
		{
			Map.Entry<String,String> entry = iter2.next();
			
			String key = entry.getKey();
			String value = entry.getValue();
			
			System.out.println(key + ":"+ value);
			
		}
	
	}

}