Collections Framework
Lists, sets, maps and queues — Java's standard data structures.
Easy
The java.util collections share common interfaces — List, Set, Map, Queue — so you can swap implementations without changing the code that uses them:
List<Integer> readings = new ArrayList<>();
Set<String> tags = new HashSet<>();
Map<String, Integer> pins = new HashMap<>();
Sub-topics (2)
ArrayList and LinkedList
Two List implementations with different performance trade-offs.
Easy♥ 0🔖 0💬 0
HashMap
Key–value storage with constant-time average lookups using hashing.
Intermediate♥ 0🔖 0💬 0
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