Java遍歴Mapの4つの方法と比較

Java遍歴Mapの4つの方法と比較

package cn.sf.util;

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

public class TestMap {

	/**
	 *      for-each     entries   
	 *                          。         
	 */
	public void testMap1(){
		Map<String, String> map = new HashMap<String, String>();
		map.put("map1", "1");
		map.put("map2", "2");
		map.put("map3", "3");
		
		Set<String> keys = map.keySet();
		for (String key : keys) {
			System.out.println(key+"---"+map.get(key));
		}
	}
	/**
	 *     :     map      ，     keySet values     
	 *  entrySet  
	 */
	public void testMap2(){
		Map<String, String> map = new HashMap<String, String>();
		map.put("map1", "1");
		map.put("map2", "2");
		map.put("map3", "3");
		
		Set<String> keys = map.keySet();
		for (String key : keys) {
			System.out.println("key:"+map.get(key));
		}
		for (String value :  map.values()) {
			System.out.println("value:"+value);
		}
	}
	/**
	 *    ：  Iterators
	 */
	public void testMap3(){
		Map<String, String> map = new HashMap<String, String>();
		map.put("map1", "1");
		map.put("map2", "2");
		map.put("map3", "3");
		Iterator<Entry<String, String>> iterators = map.entrySet().iterator();
		while(iterators.hasNext()){
			Entry<String, String> entry = iterators.next();
			System.out.println(entry.getKey()+"---"+entry.getValue());
		}
	}
	
	/**
	 *     :       (   )
	 */
	public void testMap4(){
		Map<String, String> map = new HashMap<String, String>();
		map.put("map1", "1");
		map.put("map2", "2");
		map.put("map3", "3");
		
		for (Map.Entry<String, String> entry : map.entrySet()) {
			System.out.println(entry.getKey()+"--"+entry.getValue());
		}
	}
	public static void main(String[] args) {
		TestMap testMap = new TestMap();
		testMap.testMap1();
		System.out.println();
		testMap.testMap2();
		System.out.println();
		testMap.testMap3();
		System.out.println();
		testMap.testMap4();
	}
}