Java Collections Tutorial

This tutorial describes the Java Collections Framework. Here, you will learn what collections are and how they can make your job easier and programs better. You'll learn about the core elements — interfaces, implementations, aggregate operations, and algorithms — that comprise the Java Collections Framework.

The Java Collections Tutorial source code examples have been written using JDK 8 or later. Source code examples and practices described in this tutorial are well tested in our development environment.

Getting Started

• Collections Framework in Java

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

List Implementations

General-Purpose List Implementations:

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

Special-Purpose List Implementations:

• Collections Framework - CopyOnWriteArrayList

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

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

Sorting

• Guide to Algorithms used in Java Library
• Guide to Comparable Interface
• Guide to Comparator Interface
• Sorting in Collections with Examples

Aggregate Operations(Streams)

• Collections Aggregate Operations
• Stream Reduction Operations

Collections Helper/Utility Classes

• java.util.Collections Class API Guide(Development)

          - Sorting

          - Shuffling

          - Routine Data Manipulation

          - Searching

          - Composition

          - Finding Extreme Values

• 18 Useful Collections Utility Methods (Development)
• Java CollectionUtils Class(Development)

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]

Collections Examples

• Different Ways to Iterate over List, Set and Map in Java
• 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]

Collections Differences

• Difference between LinkedList vs ArrayList in Java
• Difference between List and Set in Java Collection
• Difference between Stack and Queue Data Structure in Java
• Difference between HashMap and HashSet in Java
• Difference between TreeSet, LinkedHashSet, and HashSet in Java with Example
• Difference between EnumMap and HashMap in Java
• Difference between HashMap and HashSet in Java
• Difference between ArrayList and Vector in Java
• Difference between HashMap, LinkedHashMap, and TreeMap in Java
• Difference between PriorityQueue and TreeSet in Java?
• What is the difference between Enumeration and Iterator in Java?
• What is the difference between HashMap and Hashtable in Java?
• Difference between fail-fast Iterator vs fail-safe Iterator in Java 

Best Practices and Interviews

• Java Collection Framework Best Practice  (Best Practice)
• Difference between Array vs ArrayList in Java (interview)
• How the Size of the ArrayList Increases Dynamically? (interview)
• How To Remove Duplicate Elements From ArrayList In Java? (interview)