Map集合的三种遍历方式

package day20;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
public class MapTraverse {
	public static void main(String[] args) {
		String[] str = {"I love you","You love her","she loves him","He loves him"};
		Map<Integer, String> map = new HashMap();
		for(int i = 0; i < str.length; i++){
			map.put(i, str[i]);
		}
		System.out.println("the output is traverse0(): ");
		traverse0(map);
		System.out.println("the output is traverse1(): ");
		traverse1(map);
		System.out.println("the output is traverse2(): ");
		traverse2(map);
	}
	//1.利用keySet()方法遍历
	public static void traverse0(Map<Integer,String> map){
		Set<Integer> s = map.keySet();
		Iterator<Integer> it = s.iterator();
		int key;
		String value;
		while(it.hasNext()){
			key = it.next();
			value = map.get(key);
			System.out.println(key + ":\t" + value);
		}
	}	
	//2.利用entrySet进行遍历
	public static void traverse1(Map<Integer,String> map){
		Set<Entry<Integer, String>> s = map.entrySet();
		int key;
		String value;
		Entry<Integer,String> entry;
		Iterator<Entry<Integer,String>> it = s.iterator();
		while(it.hasNext()){
			entry = it.next();
			key = entry.getKey();
			value = entry.getValue();
			System.out.println(key + ":\t" + value);
		}
	}	
	//3.foreach
	public static void traverse2(Map<Integer,String> map){
		int key;
		String value;
		for(Map.Entry<Integer, String> entry : map.entrySet()){
			key = entry.getKey();
			value = entry.getValue();
			System.out.println(key + ":\t" + value);
		}
		
	}
}