How do I iterate over a hashmap in Java?

How do I iterate over a hashmap in Java?

You can iterate over a hashmap in Java using the keySet(), entrySet(), or values() methods. Which one would you like to know more about?

Can you explain how to use entrySet()?

Sure! You can use entrySet() to get a set of entries, and then iterate through them using a for-each loop. Here's an example:

HashMap<String, Integer> map = new HashMap<>();
map.put("A", 1);
map.put("B", 2);

for (Map.Entry<String, Integer> entry : map.entrySet()) {
    System.out.println(entry.getKey() + ": " + entry.getValue());
}

What about using keySet()?

Using keySet() is also straightforward. You can get the keys and then retrieve the values. Here's how:

for (String key : map.keySet()) {
    System.out.println(key + ": " + map.get(key));
}

Are there any performance differences between these methods?

Yes, there can be performance differences. Using entrySet() is generally more efficient because it avoids the overhead of calling get() for each key. However, the difference is usually negligible for small maps.