How often do you use the HashMap data structure in your projects?

The HashMap data structure (or similar hash tables) is used very often because it provides quick access to data by key — on average in O(1) time.

In projects, HashMap is used for:

• Caching data to quickly retrieve results without recalculations.
• Storing settings or parameters, where the key is the parameter name.
• Indexing objects by a unique identifier.
• Counting the number of occurrences of elements (e.g., words in a text).

Example of usage in tests:

Map<String, Integer> wordCount = new HashMap<>();
for (String word : words) {
    wordCount.put(word, wordCount.getOrDefault(word, 0) + 1);
}

Thus, HashMap is one of the basic and frequently used tools in development and testing.