Java - going through a hash map

Question

I am in the process of updating some old Java code I havent touched in a while and have a quick question about the following code snippet:

private Map<String, Example> examples = new ConcurrentHashMap<String, Example>();

...

public void testMethod() {
    Enumeration allExamples = examples.elements();
    while (allExamples.hasMoreElements()){
    //get the next example
    Example eg = (Example) allExamples.nextElement();
    eg.doSomething();

}

It had previously used a hashtable, but I have replaced that with a thread safe hash map. My question is, what is the best way to iterate through a hashmap? as Enumeration has been deprecated. Should I just use a for each loop?

Any advice would be greatly appreciated.

for each is the right answer. But you do have an Iterator available if you want something more. — Lee Meador, Mar 18 '13 at 15:24
there's also http://stackoverflow.com/questions/1066589/java-iterate-through-hashmap — NPE, Mar 18 '13 at 15:25

PermGenError · Answer 1 · 2013-03-18T15:25:53.493

4

yep use a for-each loop, for-each/enhanced loop was introduced for the purpose of iterating over a collection/arrays. But you can only iterate over a collection using for-each if and only if your collection implements Iterable interface.

for(Map.Entry<String, Example> en: example.entrySet()){
System.out.println(en.getKey() + "  " + en.getValue());
}

edited Mar 18 '13 at 15:25

answered Mar 18 '13 at 15:23

PermGenError

45,977
8
87
106

score 0 · Answer 2 · answered Mar 18 '13 at 15:26

0

Since you only process the values:

public void testMethod() 
{
    for (Example ex : allExamples.values())
    {
        ex.doSomething();
    }
}

answered Mar 18 '13 at 15:26

Robin

24,062
5
49
58

Java - going through a hash map

2 Answers2