map循环

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package excelTest;

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

/**
 * map循环
 * @author YangTG
 *
 */
public class MapForEach {
	
	public static void main(String[] args) {
		Map<String,String> map = new HashMap<String,String>();
		map.put("a", "1");
		map.put("b", "2");
		map.put("c", "3");
		map.put("d", "4");
		map.put("e", "5");
		
		//1 foreach循环,要判断map是否为null，不然会空指针异常
		
		for (Entry<String, String> ma: map.entrySet()) {
			System.out.println("key:"+ma.getKey()+",value:"+ma.getValue());
		}
		System.out.println("-------------------------------------------------------");
		//iterator迭代
		//1泛型
		Iterator<Entry<String, String>> itera = map.entrySet().iterator();
		while (itera.hasNext()) {
			Entry<String, String> entry = itera.next();
			System.out.println("key:"+entry.getKey()+",value:"+entry.getValue());
		}
		System.out.println("------------------------------------------------------");
		//2使用泛型
		Iterator itera1 = map.entrySet().iterator();
		while(itera1.hasNext()){
			Entry entry = (Entry) itera1.next();
			String key = (String) entry.getKey();
			String value = (String) entry.getValue();
			System.out.println("key:"+key+",value:s"+value);
		}
		
		
	}
}