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Lesson 6 - Dictionaries (maps) and sets in Java

In the previous lesson, Multidimentional arrays in Java, we introduced and tried the linked list and then made a turn to Multidimensional arrays in Java. Today's Java tutorial's going to be about dictionaries (maps) and sets.

Dictionaries (maps)

The idea of the dictionary is that we often need to access an element using a key. This concept works the same as with an array where the keys (indexes) are numeric. The dictionary allows us to index using any data type, e.g. a string. We then access the elements of the collection using these strings. An analogy can be found in a real paper dictionary where we have each string word associated with the translation, explanation, other meanings, etc.

The data in this collection is stored in a special way known as hashing. This approach allows us to


 

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In this Java tutorial, we'll introduce dictionaries and sets, describe the HashMap and HashSet classes and try these new collections on examples.

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