Longest Alphabetical Substring in Java
The challenge
Find the longest substring of a string where characters are in non-decreasing alphabetical order. If multiple substrings share the …
Read Article →Java
345 articles about java development, tools, and best practices
Permutations Alphabetically (Java)
The challenge
Given a word (a string of lowercase letters), return all its permutations in alphabetical order. Do not use built-in permutation …
Read Article →Find Number With Most Digits in Java
The challenge
Given an array of positive integers, return the number with the most digits. If two or more numbers share the highest digit count, …
Read Article →Everything you need to know to Master API Creation
Introduction to APIs
An API (Application Programming Interface) is a set of rules and protocols that allows different software applications to …
Read Article →Python vs Rust vs Go vs Java: Compared
1. Introduction
Welcome to our Programming Languages Series! In this series, we’ll explore various programming languages, understand their …
Read Article →Python vs Java Performance: Programming Powerhouses
In the vast landscape of programming languages, Python and Java have emerged as titans, offering robust solutions for a wide range of applications. …
Read Article →How to learn Java in 1 day
Learning Java in one day is not a realistic goal, as Java is a complex programming language that requires time and practice to master. However, here …
Read Article →How to Find the nth Reverse Number in Java
The challenge
Reverse Number is a number which is the same when reversed.
For example, the first 20 Reverse Numbers are:
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, …How to Find the Sum of Intervals in Java
The challenge
Write a function called sumIntervals/sum_intervals() that accepts an array of intervals, and returns the sum of all the interval …
How to Compile Multiple Java Files from a Single Command in Java
If you need to compile multiple Java files using a single command, then you can do the following.
First, it’s good to learn how to compile a …
Read Article →How to Convert JSON to a Java Object
If you need to convert JSON to a Java Object, then you can do one of the following:
Option 1 – Using Gson
import com.google.gson.Gson;
public class …How to Calculate Powers of Integers in Java
If you need to calculate the powers of Integers in Java, then you can do one of the following:
Option 1 – Using for loops
public class Power { …How to Get Today’s Date in Java
If you need to get today’s date in Java, then you can do one of the following:
Option 1 – Using LocalDate
import java.time.LocalDate;
public …How to Make a Java Jar File Executable
Let’s say you have a Java project as follows:
package ms.ao.something;
public class MyProject {
public static void main(String...args) …How to Read a File Line by Line in Java
If you need to read a file line by line in Java, then you can use one of the following three (3) options.
Option 1
You can use the FileReader and …
How can I clear or empty a StringBuilder
You can use Java’s StringBuilder to create and manipulate Strings as follows:
StringBuilder sb = new StringBuilder(); …How to Convert Array to String in Java
If you need to convert an array to a string in Java, then you could look at a solution like this:
String stringArray[] = {"Hello ", " …How to Base64 Encode a String in Java
Quick solution
In short, you can just do this:
new String(Base64.getEncoder().encode(bytes));
Examples and an explanation
In Java 8 and above, you …
Read Article →How to Generate a Random String in Java
Java provides many ways to generate random strings.
1. Using Apache Commons
public void generatingRandomAlphanumericString_ApacheCommons() { …How to Parse HTML/CSS Colors in Java
The challenge
In this challenge, you parse RGB colors represented by strings. The formats are primarily used in HTML and CSS. Your task is to …
Read Article →Solving Simple Transposition in Java
The challenge
Simple transposition is a basic and simple cryptography technique. We make 2 rows and put first a letter in Row 1, the second in Row 2, …
Read Article →The Difference of 2 in Java
The challenge
The objective is to return all pairs of integers from a given array of integers that have a difference of 2.
The resulting array should …
Read Article →How to Make the Deadfish Swim in Java
The challenge
Write a simple parser that will parse and run Deadfish.
Deadfish has 4 commands, each 1 character long:
iincrements the value …
How to Write Number in Expanded Form in Java
The challenge
You will be given a number and you will need to return it as a string in Expanded Form.
Examples:
Challenge.expandedForm(12); // Should …