如何迭代或循环Map

<p>有多种方法可以在Java中迭代Map。如下所示 – </p> <ul> <li>KeySet和Iterator</li><li>EntrySet和for-each循环</li><li>Stream（在Java8中引入）</li></ul> <p>在本教程中，我们将使用Iterator来迭代Map，</p> <p>文件：<em>IterateMapExample.java</em> -</p>

import java.util.HashMap; import java.util.Iterator; import java.util.Map; import java.util.Map.Entry; import java.util.Set;  public class IterateMapExample {     public static void main(String[] args) {         Map<String, String> daysMap=new HashMap<>();         daysMap.put("1", "MON");         daysMap.put("2", "TUE");         daysMap.put("3", "WED");         daysMap.put("4", "THU");         daysMap.put("5", "FRI");         daysMap.put("6", "SAT");         daysMap.put("7", "SUN");          /* Iterating map using  Set Collection and Iterator*/         System.out.print("Using Set and Iterator : ");         Set<String> keysSet=daysMap.keySet();         for (Iterator<String> iterator=keysSet.iterator();iterator.hasNext();) {             String key=iterator.next();             System.out.print("("+key+","+daysMap.get(key)+") ");         }          /* Iterating map using  EntrySet and For Each loop*/         System.out.print("/nUsing EntrySet and For Each loop : ");         Set<Entry<String, String>> entries=daysMap.entrySet();         for (Entry<String, String> entry : entries) {             System.out.print("("+entry.getKey()+","+entry.getKey()+") ");         }          /* Iterating map using Stream*/         System.out.print("/nUsing Stream : ");         daysMap.forEach((key,value)->System.out.print("("+key+","+value+") "));     } } 

<p>执行上面示例代码，得到以下结果 – </p>

Using Set and Iterator : (1,MON) (2,TUE) (3,WED) (4,THU) (5,FRI) (6,SAT) (7,SUN)  Using EntrySet and For Each loop : (1,1) (2,2) (3,3) (4,4) (5,5) (6,6) (7,7)  Using Stream : (1,MON) (2,TUE) (3,WED) (4,THU) (5,FRI) (6,SAT) (7,SUN)