Home > Java > Inspecting HashMaps

Inspecting HashMaps

One query which seems to turn up frequently in the blog stat reports is how to iterate or print a HashMap so that its contents are visible. The bottom line is that HashMap itself doesn’t directly support an iterator. However the getKeys() method of HashMap returns a Set object which can be iterated without any problem.

public void printHashMap(HashMap ha)
Set keys = ha.keySet();
Iterator it = keys.iterator();

String sx = "";

while (it.hasNext()) {
          Object key = it.next();
        String sKey = key.toString();
        Object val = ha.get(key);
        String kVal = val.toString();
        sx += sKey + " - " + kVal + "\n";



Obviously once you’ve got the trick of handing off the iteration of a HashMap to the Set returned by getKeys() life gets altogether more comfortable; no longer is that HashMap a ferociously daunting object lurking in memory,a monster which you can’t be certain at any time as to what it contains, but it becomes an altogether more amenable and house-trained creature.

I’ll get round to a few more of these over the coming weeks, in between writing some more semantic parsing code which I’ll also be blogging about.

Categories: Java Tags: , ,
  1. No comments yet.
  1. No trackbacks yet.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: