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Java Collections Framework

April 5, 2026

Collections Framework

Unified architecture for storing/manipulating groups of objects.

Collection Hierarchy

List list = new ArrayList<>();
Set set = new HashSet<>();
Map map = new HashMap<>();

list.add("Java");
set.add(1);
map.put("age", 25);

Key Points

List: ordered, duplicates allowed.
Set: unique elements only.
Map: key-value pairs.
Generics ensure type safety.

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