How to create ArrayList from Array in Java
The problem
If you have a traditional array, that looks something like the following:
A[] array = {new A(1), new A(2), new A(3)};
And you would like …
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How to Remove all Vowels from a String in Java
The challenge
Remove all vowels from the string.
Vowels:
a e i o u
A E I O U
The solution in Java code
Option 1:
public class VowelRemoval {
public …How to Solve Max-Min Arrays in Java
The challenge
You are given an array of unique elements, and your task is to rearrange the values so that the first max value is followed by the first …
Read Article →How to do Basic Encryption in Java
The challenge
The most basic encryption method is to map a char to another char by a certain math rule. Because every char has an ASCII value, we can …
Read Article →How to Find the Squares in Java
The challenge
Complete the function that takes an odd integer (0 < n < 1000000) which is the difference between two consecutive perfect squares, …
How to Get Longest Word in Sentence in Java
The challenge
When given a string of space-separated words, return the word with the longest length.
If there are multiple words with the longest …
Read Article →Maximum Different of Int-Array in Java
The challenge
You must implement a function that returns the difference between the biggest and the smallest value in a list(lst) received as a …
Read Article →Indexed Capitalization in Java
The challenge
Given a string and an array of integers representing indices, capitalize all letters at the given indices.
Example: …
Read Article →How to Spacify a String in Java
The challenge
Modify the spacify function so that it returns the given string with spaces inserted between each character.
spacify("hello …How to Validate Usernames with Regex in Java
The challenge
Write a simple regex to validate a username. Allowed characters are:
- lowercase letters,
- numbers,
- underscore
Length should be between 4 …
Read Article →Sort Lexicographical Order of Substrings in Java
The challenge
Given two arrays of strings a1 and a2 return a sorted array r in lexicographical order of the strings of a1 which are substrings of …
How to Perform Alphabetical Addition in Java
The challenge
Your task is to add up letters to one letter.
The function will be given an array of single-character Strings, each one being a letter …
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