"Not tired yet? Let's carry on, then. I'd like to give you more details about Set and Map and what they can do."
"Set is a set, a group of unnumbered objects. The main feature of a Set is that it only contains unique objects, i.e. each element of the set is different. Here are operations you can perform on a set:"
|Add element(s)||add(), addAll()|
|Remove element(s)||remove(), removeAll()|
|Check for the presence of element(s)||contains(), containsAll()|
"And that's it?"
"Well, yes. You can also use the size() method to find out how many elements are in the set."
"What about Map?"
"Map is a set of pairs. It's like a Set, except it's a set of key-value pairs rather than unique elements. The only limitation is that each «key» must be unique. A Map can't contain two pairs with the same keys."
"Here's what we can do with Map:"
|Get a set of all pairs||entrySet()|
|Get a set of all keys||keySet()|
|Get a set of all values||values()|
|Add a pair||put(key, value)|
|Get the value for the specified key||get(key)|
|Check whether the specified key is present||containsKey(key)|
|Check whether the specified value is present||containsValue(value)|
|Check whether the Map is empty||isEmpty()|
|Clear the Map||clear()|
|Remove the value for the specified key||remove(key)|
"This is much more interesting than Set."
"Yes. Although Map isn't as popular as List, it is used in many tasks."
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