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Algorithms and Data Structures

On this page, you find an overview of how-tos and tutorials about Java.

Tree Data Structure

The following articles describe various tree data structures. A tree is a hierarchical structure with a root node and its children, which in turn can have children of their own and thus form subtrees.

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Red-Black Tree
(Fully Explained + with Java Code)

What is a red-black tree? How do you insert, search and delete nodes? By which rules is the tree balanced? How to implement a red-black tree in Java? And how do...
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AVL Tree
(+ Java Code Examples)

What is an AVL tree? How do you calculate a node's balance factor? How does rotation work and how is an AVL tree balanced? How to implement an AVL tree in Java?
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Binary Search Tree
(+ Java Code Examples)

What is a binary search tree (BST)? How do you insert new elements, how do you search for them, and how do you delete them? How do you implement a BST in Java?...
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Binary Tree
(+ Java Code Examples)

What is a binary tree, and what types exist? How to implement a binary tree in Java? What are its operations? What are pre-order, in-order, post-order, and...

Shortest Path Algorithms

Pathfinding or shortest path algorithms are used to find a path (or the shortest path) between two nodes within a graph.

SHORTEST
PATH

Algorithms

What you'll learn
  • What is the difference between "shortest path" and "pathfinding"?
  • Which pathfinding algorithms are there?
  • How do the most important pathfinding algorithms work (explained step by step)?
  • When do you use which algorithm?
  • How to determine the time complexities of the pathfinding algorithms?
  • How to implement pathfinding algorithms in Java?
  • What are "negative cycles" and how are they identified?

Algorithms and Data Structures in General

This category covers general articles about algorithms without any specific type of algorithm in mind, e.g., classifications of algorithms.

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Array vs. Linked List

What is the difference between Array and Linked List? What are the advantages and disadvantages? When should you use which data structure?
Binary search with Java examples

Binary Search (+ Java Code Examples)

How does binary search work? How to implement binary search in Java? What binary search functions does the JDK provide?...
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Big O Notation and Time Complexity – Easily Explained

In this article, I will explain the big O notation (and the time and space complexity described with it) only using...

Sorting Algorithms

If you need a refresher on how the most common sorting algorithms work and how they differ, this series is for you.

Sorting

Algorithms

What you'll learn
  • What are the most common sorting methods?
  • In which characteristics do they differ?
  • How to sort arrays and collections in Java?
  • How each sorting algorithm works (using lots of visualizations and examples).
  • How to derive a sorting algorithm's time complexity, without complicated maths.
  • How to implement each sorting algorithm in Java.

Stack

In this tutorial series, you will learn everything about the abstract data type "stack", how to use it, and how to implement your own stack classes in Java.

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Stack Data Structure

In this tutorial, you will learn everything about the abstract data type "stack", how to use it, and how to implement your own stack in Java.
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Stack Class in Java
(+ Code Examples)

How to use Java's Stack class (with an example)? Why should you stop using java.util.Stack? What are the alternatives?
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Stack Implementation in Java

In this tutorial, you will learn how to implement a stack in Java - with an ArrayDeque, an Array, a LinkedList and a Queue.
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Implement a Stack Using an Array

How to implement a stack based on an array in Java (without Java Collections classes)? How do you make the array grow on demand?
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Implement a Stack Using a Linked List

How to implement a stack using a linked list? What are the advantages and disadvantages? Tutorial with images and Java code examples.
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Implement a Stack Using Queues

How to implement a stack with a queue (better said: with two queues)? Tutorial with images and Java code examples.
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Reverse a Stack Using Recursion

How to reverse the order of the elements in a stack using recursion (i.e., without iteration)? Tutorial with images and Java code examples.
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Stack vs. Queue

What are the differences between the stack and queue data structures? How do the corresponding Java interfaces and classes differ?

Queue

In this tutorial series, you will learn everything about the abstract data type "queue", which methods it provides, how to use queues, when to use which queue implementation and how to program your own queues in Java.

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Queue Data Structure

In this tutorial, you will learn everything about the abstract data type "Queue", enqueue and dequeue operations, using illustrative Java examples.
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Queue Interface in Java
(+ Code Examples)

How to create and use a queue in Java? What methods does the Queue interface offer? Which queues exist in the JDK? With sample code!
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BlockingQueue Interface in Java
(+ Code Example)

How to use Java's BlockingQueue interface? What methods does it provide? What are blocking, unblocking, bounded, and unbounded queues?
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Java ConcurrentLinkedQueue
(+ Code Examples)

How to use Java's ConcurrentLinkedQueue? How does it work? What are its characteristics? When should you use it?
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Java PriorityQueue
(+ Code Examples)

What is a priority queue? How does Java's PriorityQueue work? What are its characteristics? How do you use it, and how do you configure it?
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Java LinkedBlockingQueue
(+ Code Examples)

How to use Java's LinkedBlockingQueue? How does it work? What are its characteristics? When should you use it?
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Java ArrayBlockingQueue – What is it for? + How to use it?

How to use Java's ArrayBlockingQueue? How does it work? What are its characteristics? When should you use it?
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Java PriorityBlockingQueue
(+ Code Examples)

How to use Java's PriorityBlockingQueue? How does it work? What are its features? When should you use it?
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Java DelayQueue
(+ Code Examples)

How to use Java's DelayQueue? How does it work? What are its features? When should you use it?
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SynchronousQueue in Java
(+ Code Examples)

How to use Java's SynchronousQueue? How does it work? What are its characteristics? When should you use it?
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LinkedTransferQueue in Java
(+ Code Examples)

How to use Java's LinkedTransferQueue? How does it work? What are its characteristics? When should you use it?
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Queue Implementations in Java – Which One to Use?

Which Queue implementations are available in the JDK? How do they differ? In which cases should you use which implementation?
Implementing a Queue with two Stacks - Feature Image
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Implementing a Queue Using a Stack

How to implement a queue with a stack (more precisely: with two stacks)? Tutorial with illustrations and Java code examples.
Implementing a Queue with a Linked List - Feature Image
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Implementing a Queue Using a Linked List

How to implement a queue using a linked list? How to enqueue and dequeue elements? Tutorial with images and Java code examples.
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Implementing a Queue Using an Array

How to implement a queue based on an array in Java (without Java collections classes)? How does the array grow on demand?
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Implementing a Priority Queue Using a Heap

How to implement a priority queue with a heap in Java? Illustrative explanation with diagrams and Java source code.

Deque

In this tutorial series, you will learn everything about the abstract data type "deque", which methods it provides, how to use deques, when to use which deque implementation and how to program your own deques in Java.

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Deque Data Structure

In this tutorial, you will learn everything about the abstract data type "deque", which deques exist in Java, and how to implement deques yourself.
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Deque Interface in Java
(+ Code Examples)

How to create and use a deque in Java? What methods does the Deque interface provide? Which deques exist in the JDK? With sample code!
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BlockingDeque Interface in Java
(+ Code Example)

How to use the BlockingDeque interface in Java? Overview of all blocking methods and comparison with the BlockingQueue interface.
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Java ArrayDeque – What is it for? + How to use it?

How to use the Java ArrayDeque? How does it work? What are its characteristics? Comparison with LinkedList. When should you use it?
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Java LinkedList as Deque
(+ Code Examples)

How to use the Java LinkedList as a deque? How does it work? What are its characteristics? When should you use it as a deque?
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Java ConcurrentLinkedDeque
(+ Code Examples)

How to use the Java ConcurrentLinkedDeque? How does it work? What are its characteristics? When should you use it?
LinkedBlockingDeque - Feature Image
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Java LinkedBlockingDeque
(+ Code Examples)

How to use the Java LinkedBlockingDeque? How does it work? What are its characteristics? When should you use it?
Java Deque Implementations - Which one to use?
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Deque Implementations in Java – Which One to Use?

Which Deque implementations exist in the JDK? How do they differ? In which cases should you use which implementation?
Implementing a Deque Using an Array - Feature Image
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Implement a Deque Using an Array

How to implement a deque based on an array in Java (without Java collections classes)? How does the array grow on demand?
Deque vs. Stack - Feature Image
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Java Deque vs. Stack

What are the differences between the data structures and Java classes Deque and Stack? Why should we use only Deque in Java?
Deque vs. Queue - Feature Image
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Java Queue vs. Deque

What are the differences between the data structures deque and queue? And how do the corresponding Java interfaces differ?

Data Structures in Java

What are data structures? A data structure is a collection of related data values and their relationships with each other. It provides operations to read or modify the data.

Java data structures are, for example, collections, maps, and sets, trees, queues, deques, and stacks.

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Array Length in Java

How to find the length of an array in Java? How do you set the length? How much memory does an array occupy and what is the maximum size?
declare and initialize arrays in java
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How to Initialize Arrays in Java

How to declare and initialize arrays in Java? How to copy and fill them? How to convert lists, sets and streams into arrays?
Stack, Queue, Deque - Feature Image
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Stack, Queue, Deque in Java

How do the stack, queue and deque data structures work? Which implementations are available in the JDK? Which one should you use when?

Advent of Code

In the following articles, you will find object-oriented, test-driven Java solutions for Advent of Code:

advent of code 2022 solutions
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Advent of Code 2022 – Object-oriented Solutions in Java

Here you can find all solutions to Advent of Code 2022. All tasks are implemented in an object-oriented and test-driven way in Java.
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Advent of Code 2015 – Object-oriented Solutions in Java

Here you can find all solutions to Advent of Code 2015. All tasks are implemented in an object-oriented and test-driven way in Java.