Map的基础

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遍历Map集合的两种方法:

1.第一种方法:

public class MapDeom {/** * @param args  * @author chenwenlong */public static void main(String[] args) {Map<String,String> map = new HashMap<String,String>();map.put("01","哈哈");map.put("02","乐乐");//获取全部键Set<String> keySet = map.keySet();//通过keySet获取键//for遍历for(Iterator<String> it =keySet.iterator();it.hasNext();){String key = it.next();String value = map.get(key);System.out.println(key+"---"+value);}//foreach遍历键for(String key:keySet){//根据键获取值String value = map.get(key);System.out.println(key+"=="+value);}}}

2.第二种方法:

public static void main(String[] args) {Map<String,String> map = new HashMap<String,String>();map.put("01","哈哈");map.put("02","乐乐");Set<Entry<String,String>> entrySet = map.entrySet();//entrySet方法:讲map集合映射关系存储到set集合中Iterator<Entry<String, String>> it = entrySet.iterator();               //遍历set集合中映射关系对象while(it.hasNext()){Map.Entry<String, String> entry = it.next();//取到映射关系对象//获取键String key = entry.getKey();//获取值String value = entry.getValue();System.out.println(key+"---->"+value);}

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