Java Collections Tutorial

This tutorial is a one-stop shop for all the Java collections interfaces, implementation classes, interface questions and answers, practical examples, utility methods, etc.

The Java Collections Tutorial source code examples have been written using the latest version of JDK. Source code examples and practices described in this tutorial are well-tested in our development environment.

YouTube Video - Java Collections Framework Course

1. Core Interfaces

• Collections Framework - The Collection Interface
• Collections Framework - The Set Interface 
• Collections Framework - The SortedSet Interface 
• Collections Framework - The List Interface
• Collections Framework - The Queue Interface
• Collections Framework - The Deque Interface
• Collections Framework - The Map Interface 
• Collections Framework - The SortedMap Interface

2. List Implementations

General-Purpose List Implementations:

• Collections Framework - ArrayList Class
• Collections Framework - LinkedList Class

Special-Purpose List Implementations:

• Collections Framework - CopyOnWriteArrayList

3. Set Implementations

General-Purpose Set Implementations:

• Collections Framework - HashSet Class
• Collections Framework - LinkedHashSet Class
• Collections Framework - TreeSet Class

Special-Purpose Set Implementations:

• Collections Framework - CopyOnWriteArraySet
• Collections Framework - EnumSet

4. Map Implementations

General-purpose Map Implementations:

• Collections Framework - HashMap Class
• Collections Framework - LinkedHashMap Class
• Collections Framework - TreeMap class

Special-Purpose Map Implementations:

• Collections Framework - EnumMap
• Collections Framework - WeakHashMap
• Collections Framework - IdentityHashMap

5. Sorting

• Guide to Comparable Interface
• Guide to Comparator Interface
• Sorting in Collections with Examples

6. Aggregate Operations(Streams)

• Collections Aggregate Operations
• Stream Reduction Operations

7. Collections Helper/Utility Classes

• Java Collections Utility Class(Development)
• 18 Useful Collections Utility Methods (Development)
• Java Custom User-Defined CollectionUtils Class(Development)

8. Convert Collections Examples

• Conversion Between Array and Set in Java
• Conversion Between Array and List in Java
• Java Convert Map to Set Example
• Java Convert Map to List Example
• Java Convert Map to Array Example
• Convert a Map to an Array, List, and Set in Java
• Java 8 Convert List to Map Example
• Java 8 - Merging Two Maps Example
• Java Convert Array to String [Snippet]

9. Collections Examples

• Java LinkedHashMap Example
  
• Java HashSet Example
  
• Java LinkedList Example
  
• Java ArrayList Example
• Java Comparator Interface Example
• Java Comparable Interface Example
• Java IdentityHashMap Example
• Java WeakHashMap Example
• Java EnumMap Example
• Java CopyOnWriteArraySet Example
• Java EnumSet Class Example
• Guide to Java 8 forEach Method
• Different Ways to Iterate over a List in Java [Snippet]
• Different Ways to Iterate over a Set in Java [Snippet]
• Different Ways to Iterate over a Map in Java [Snippet]
• Iterate over TreeSet in Java Example
• Iterate over LinkedHashSet in Java Example
• Remove the First and Last Elements of LinkedList in Java
• Iterate over LinkedList using an Iterator in Java
• Search an Element in an ArrayList in Java
• Iterate over ArrayList using Iterator in Java
• Remove Element from HashSet in Java
• Iterating over a HashSet using Iterator
• How To Remove Duplicate Elements From ArrayList In Java?
  
• Different Ways to Iterate over List, Set, and Map in Java

10. Interview QA - Differences

• Difference Between List and Set in Java
• Difference Between Collection and Collections in Java
  
• Difference Between Array and ArrayList in Java
  
• Difference between ArrayList and LinkedList in Java
• Difference Between HashSet and LinkedHashSet in Java
• Difference Between HashSet and TreeSet in Java
• HashSet vs LinkedHashSet vs TreeSet in Java
• Difference Between HashMap and HashTable in Java
• Difference Between HashSet and HashMap in Java
• HashMap vs LinkedHashMap in Java
• Difference between HashMap, LinkedHashMap, and TreeMap in Java
• Collections vs Streams in Java

11. YouTube Video Series - Java Collections Framework in Depth Series

• Java Collections Framework in Depth - 1 - Need for Collections Framework
• Java Collections Framework in Depth - 2 - Collections Framework Hierarchy
• Java Collections Framework in Depth - 3 - Collection Interface with Coding Example
• Java Collections Framework in Depth - 4 - List Interface with Coding Example
• Java Collections Framework in Depth - 5 - ArrayList Class Overview
• Java Collections Framework in Depth - 6 - Creating an ArrayList and Adding New Elements to It
• Java Collections Framework in Depth - 7 - Creating ArrayList from Another Collection
• Java Collections Framework in Depth - 8 - Accessing Elements from an ArrayList
• Java Collections Framework in Depth - 9 - Removing Elements from an ArrayList
• Java Collections Framework in Depth - 10 - Iterating Over an ArrayList (6 Ways)
• Java Collections Framework in Depth - 11 - ListIterator Interface with Coding Example
• Java Collections Framework in Depth - 12 - CopyOnWriteArrayList Class with Coding Example
• Java Collections Framework in Depth - 13 - LinkedList Overview | ArrayList vs LinkedList
• Java Collections Framework in Depth - 14 - Create LinkedList Example | add(), and first and addLast()
• Java Collections Framework in Depth - 15 - Retrieving Elements from a LinkedList
• Java Collections Framework in Depth - 16 - Removing Elements from a LinkedList
• Java Collections Framework in Depth - 18 - HashSet Class Overview | Key Points to Note

The complete YouTube playlist at Learn Java Collections Framework

12. Best Practices and Interviews

• Java Collection Framework Best Practice  (Best Practice)
• How does the Size of the ArrayList Increase Dynamically? (interview)
• How To Remove Duplicate Elements From ArrayList In Java? (interview)

References

• https://docs.oracle.com/en/java/javase/18/docs/api/java.base/java/util/package-summary.html
• https://docs.oracle.com/javase/tutorial/