How to sort an Array in Java? Ascending and Descending Order Example

As a Java programmer, quite often you would need to sort array in Java luckily java.util.Arrays class provides several utility methods to sort an array in Java. You can sort different types of array in Java like array of primitive data types, object or int, String, etc. Arrays are in java.util package and exposed all sorting related methods as static utility functions. you can access sort() as Arrays.sort() and just pass your array and it will sort that array object by comparing them in the order implemented in the compareTo() method if the class implements Comparable interface. 

How to loop through an Array in Java? Example Tutorial

Hello there, If you want to loop over an array in Java but not sure how to do that then you have come to the right place. Earlier, I have shared many Java array tutorials and the best Java courses for beginners, and today, I am going to teach you how to iterate over an array in Java. There are multiple ways to loop over an array in Java, like you can use a for loop, an enhanced for loop, a while loop, or a do-while loop. Since while and do-while needs a condition to terminate they often depend upon the content of the array like stop when the current element is null or even or odd etc. If you just want to iterate over an array to access each element like loop over an array and print each entry then you should use either for loop or the enhanced for loop.

How to declare and initialize a List with values in Java (ArrayList/LinkedList) - Arrays.asList() Example

Hello guys, today, I am going to share with you a useful tip to initialize a List like ArrayList or LinkedList with values, which will help you a lot while writing unit tests and prototypes. Initializing a list while declaring is very convenient for quick use, but unfortunately, Java doesn't provide any programming constructs like the collection literals of Scala, but there is a trick which you can use to declare and initialize a List at the same time. This trick is also known as initializing a List with values. I have used this trick a lot while declaring list for unit testing and writing demo programs to understand an API etc and today I'll you'll also learn that.

How to implement Skip List in Java? Example Tutorial

Hello friends, we meet again today. hope you all are excited and ready for today's journey. Today, we are gonna learn something that is not very common. It is used not very common, but, if used, it is a great strength to our time complexity reduction. So, what's the wait? Let's start! So, suppose we have a linked list with us which has 10 million records. Now, for searching a particular node, the time taken would be O(N). Where N is the size of the list. Similarly, the time taken for deletion of a Node, Insertion at a particular Node will also take O(N) time. Can we reduce it?

How to find If Linked List Contains Loop or Cycle in Java? Example Solution

Write a Java program to check if a linked list is circular or cyclic,  and how do you find if a linked list contains loop or cycles in Java are some common linked list related data structure interview questions asked in various Java Interviews. This is sometimes asked as a follow-up question of basic linked list questions like inserting an element at the beginning, middle and end of a linked list or finding the length of linked list. In order to solve linked list related algorithmic questions in Java, you need to be familiar with the concept of singly linked list, doubly linked list, and circular linked list. Until stated specifically, most questions are based on a singly linked list. For those who are not familiar with the linked list data structure, its a collection of nodes.

How to use Array in Java? Example Tutorial

The array is one of the most important data structures in any programming language, at the same time different programming languages implement and treat the array differently. Anyone who is done some programming knows the value of an array and the importance of knowing about array type, using them in their program. Together with a linked list, the array forms a set of basic data structures. Though Java offers excellent Collection API and some of the collection classes like ArrayList and  HashMap, they are internally based on the array.

Top 15 Data Structures and Algorithm Interview Questions Answers for Java Programmer

Data structures and algorithm questions are an important part of any programming job interview, be it a Java interview, a C++ interview, or any other programming language. Since data structures are core programming concepts, it's mandatory for all programmers, to know basic data structures like the stack, linked list, queue, array, tree, and graph. Though trees and graphs are on the tougher side, I still see programmers get familiar will all these. Any list of programming job interview questions is incomplete without questions from data structures and algorithms. Similarly, while going on questions from data structure you may get some programming exercise as well e.g. swapping numbers without temp variable.

Difference between Stable and Unstable Sorting Algorithm - MergeSort vs QuickSort

Recently in one interview, after some initial questions about sorting algorithms e.g. how do you write QuickSort or the difference between QuickSort and MergeSort, the interviewer asked about do you understand the difference between stable and unstable sorting algorithms? This question was new to my reader, so he says, Sorry, never heard about that. The story ended there, and Interviewer moved on to the next question but like many of us, my reader went on to find more unanswered questions and ultimately he asks me what is the meaning of a stable and unstable sorting algorithm? Some of you might be heard about it and many of you might not know about this distinction, I'll try to answer this question in this article.

How to Count Number of Leaf Nodes in a Binary Tree in Java ? [ Iterative and Recursive Solution]

Hello guys, today I am going to talk about an interesting binary tree-based coding problem from Programming Job interviews. If you have attended a couple of technical interviews then there is a good chance that you already have seen this question about counting the number of leaf nodes in a binary tree. If you know how to solve this problem then it's well and good but if you haven't don't worry, you will learn in this article. If you follow this blog then you might know that I have discussed a lot of data structure and algorithms problems here, including array, linked list, hash table, binary tree, and binary search tree. 

6 ways to declare and initialize a two-dimensional (2D) String and Integer Array in Java - Example Tutorial

Declaring a two-dimensional array is very interesting in Java as the Java programming language provides many ways to declare a 2D array and each one of them has some special things to learn about. For example, It's possible to create a two-dimensional array in Java without specifying the second dimension, sounds crazy right? but it's possible because a two-dimensional array in Java is nothing but an array of array. You can even create a two-dimensional array where each subarray has a different length or different type, also known as a heterogeneous array in Java. This means it's possible to create a two-dimensional array with variable column length in Java.

How to implement Bucket Sort in Java? [Solved] - Example Tutorial

In recent years, one of the questions I have increasingly seen in programming job interviews is about constant time sorting algorithms like do you know any O(n) sorting algorithm? how do they work? When I first encountered this question, I had no idea whether we can sort in constant time because even some of the fastest sorting algorithms like QuickSort or MergeSort take O(N log N) time for sorting on their average case. After some research, mainly by going through the classic CLRS book and this DS and Algorithms course by Tim Buchalka and Goran Lochert on Udemy, I come to know that there indeed are some constant time or linear time sorting algorithms like bucket sort, counting sort, and radix sort, which can sort an array in O(n) time but they work with only a special set of input.

Recursive Binary Search Algorithm in Java - Example Tutorial

The binary search algorithm is one of the most famous search algorithms in computer science. It allows you to search a value in logarithmic time i.e. O(logN), which makes it ideal to search a number on a huge list. For example, in order to search a number in a list of 1 million numbers will take around 210 comparisons compared to 1 million comparisons required by the linear search algorithm. The only thing is that the list must be sorted before you can use a binary search algorithm and it must support index-based search. 

Difference between Stack and Queue Data Structure in Java? Example

Stack and Queue are two of the important data structures in the programming world and have a variety of usage. As opposed to the array and linked list, which are considered primary data structures, they are secondary data structures that can build using an array or linked list. You can use Stack to solve recursive problems and Queue can be used for ordered processing. The difference between Stack and Queue Data structure is also one of the common questions not only in Java interviews but also in C, C++, and other programming job interviews.

Difference between Comparison (QuickSort) and Non-Comparison (Counting Sort) based Sorting Algorithms? Example

For many of you, this might be a surprise that how you can sort or arrange items without comparing them with each other, but it's possible. There are some sorting algorithms that perform sorting without comparing the elements rather than making certain assumptions about the data they are going to sort. The process is known as non-comparison sorting and algorithms are known as the non-comparison-based sorting algorithms. Non-comparison sorting algorithms include Counting sort which sorts using key-value, Radix sort, which examines individual bits of keys, and Bucket Sort which examines bits of keys. 

How to implement Post Order Traversal of Binary Tree in Java - Recursion and Iteration Example

This is the third article on tree traversal. In the last couple of articles, I have shown you how to implement preorder and inorder traversal in Java, both recursively and iteratively and today, you will learn about the post-order traversal. Out of these three main tree traversal algorithms, the post-order traversal is most difficult to implement, especially the iterative version. In postorder traversal, you first visit left subtree, then right subtree and at last you print the value of root or not. So, the value of root is always printed at last in the post-order traversal.