Java Collections and Generics

Collections manage groups of objects Provide far more functionality than basic arrays Distinct characteristics

Deletion insertion dynamic allocation size variability support for polymorphism

List

Stores objects while maintaining index and order allowing duplicates

ArrayList Possesses array characteristics with dynamic resizing Slower in terms of speed due to indexing (e.g., values inserted or deleted in the middle)

LinkedList Provides faster manipulation compared to ArrayList

Using Generics group specific types together List nick = new ArrayList<>();

Common Methods nick.add(“Value”) Adds an object nick.get(index) Accesses by index nick.size() Returns the size nick.set(index, “Value”) Modifies an index nick.contains(“Value”) Checks existence nick.clear() Clears all elements nick.isEmpty() Checks if empty

Collections Utility Class Collections.addAll(list, val1, val2, …) Adds multiple objects at once Collections.frequency(list, val) Counts occurrences Collections.min(list) Collections.max(list) Finds min/max values Collections.sort(list) Sorts the list Collections.shuffle(list) Randomizes order Collections.fill(list, val) Initializes with a value

Set

Implements set theory does not allow duplicates

Hash

An algorithm that generates unpredictable values for a given input Sorting is impossible due to unpredictable nature of generated values Nearly impossible to retrieve the original value from the hash A one-way algorithm Offers fast performance and high security

LinkedList Usage

Stack (LIFO: Last In First Out) push pop peek

Queue (FIFO: First In First Out) offer poll peek