Convert String to Camel Case using Java
The challenge
Complete the method/function so that it converts dash/underscore delimited words into camel casing. The first word within the output …
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345 articles about java development, tools, and best practices
Sort a Java Integer in Descending Order
The challenge
Your task is to make a function that can take any non-negative integer as an argument and return it with its digits in descending order. …
Read Article →Get the Sum of Digits / Digital Root using Java
The challenge
Digital root is the recursive sum of all the digits in a number.
Given n, take the sum of the digits of n. If that value has more than …
Check if Valid Sudoku Blocks in Java
The challenge of solving valid Sudoku blocks
Determine if a 9×9 Sudoku board is valid. Only the filled cells need to be validated according to the …
Read Article →FizzBuzz in Java
The challenge
Write a program that outputs the string representation of numbers from 1 to n.
But for multiples of three it should output “Fizz” …
Read Article →Python Splices reimplemented in Java
Python has a fantastic feature called slices. It allows you to work with a list, set or string by it’s index items.
E.g.:
string_sample = …Is a Valid Palindrome with Java
The challenge
Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.
Note: For the purpose of …
Read Article →Is a Valid Anagram with Java
The challenge
Given two strings s and t , write a function to determine if t is an anagram of s.
Example 1:
Input: s = "anagram", t = "nagaram" …Read Article →
How to ReImplement strStr() in Java
What we want to achieve
Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.
Example 1:
Input: …Read Article →
Third Maximum Number with Java
The challenge
Given a non-empty array of integers, return the third maximum number in this array. If it does not exist, return the maximum number. The …
Read Article →First Unique Character in a String using Java
The challenge
Given a string, find the first non-repeating character in it and return its index. If it doesn’t exist, return -1.
Examples:
s = …Read Article →
How to fix the Release Version 5 Not Supported error in IntelliJ
What do you do when you create a new Maven Java project, and when you run it, you get the following error:
Error:java: error: release version 5 not …
How to Reverse an Integer in Java
The challenge
Given a 32-bit signed integer, reverse digits of an integer.
Example 1:
Input: 123 Output: 321
Example 2:
Input: -123 Output: -321 …Read Article →
Reverse a String in-place using Java
The challenge
Write a function that reverses a string. The input string is given as an array of characters char[].
Do not allocate extra space for …
Read Article →Check if a Java array Contains Duplicates
The challenge
Given an array of integers, find if the array contains any duplicates.
Your function should return true if any value appears at least …
Read Article →The Array Height Checker Problem in Java
The challenge
Students are asked to stand in non-decreasing order of heights for an annual photo.
Return the minimum number of students that must move …
Read Article →Find the Squares of a Sorted Array in Java
The challenge
Given an array of integers A sorted in non-decreasing order, return an array of the squares of each number, also in sorted …
Sorting a Java Array by Parity
The challenge
Given an array A of non-negative integers, return an array consisting of all the even elements of A, followed by all the odd elements of …
Remove Duplicates from Sorted Array in Java
Say you have an array of primitive integers and you want to remove all duplicates.
You can find out how many non-duplicate integers are in the array …
Read Article →Replace Elements with Greatest Element on Right Side using Java
The challenge
Given an array arr, replace every element in that array with the greatest element among the elements to its right, and replace the last …
The Valid Mountain Array Problem using Java
Introducing the problem
Given an array A of integers, return true if and only if it is a valid mountain array.
Recall that A is a mountain array if …
Read Article →Find Numbers with Even Number of Digits using Java
The challenge
Given an array nums of integers, return how many of them contain an even number of digits.
Example 1:
Input: nums = [12,345,2,6,7896] …Read Article →
How to use a Java HashSet by example
What is a HashSet
A HashSet is an unordered collection containing unique elements. It has the standard collection operations Add, Remove, Contains, …
The Decoded String at Index using Java
The Challenge
An encoded string S is given. To find and write the decoded string to a tape, the encoded string is read one character at a time and …