Validate Email Address in Java

In this Java core tutorial, we learn how to use the regular expression in Java to check whether an email address is valid or not.

Check if a String contains another String in Java

Core Java classes provide different solutions that developers can use to check if a String contains another String inside it. In this article we will show you different Java code examples how to check if a String is inside another String using core Java methods such as String.contains(), String.indexOf(), String.lastIndexOf(), String.matches() and java.util.regex.Pattern class.

Replace or Remove All Digits of a String in Java using regular expression

In this article we are going to learn how to use core Java classes to remove all numeric characters from a String or replace numeric characters with other characters. We will show you different Java code examples how to use String.replaceAll() method and java.util.regex.Pattern class.

Extract Digits from a String in Java using regular expression

In this post we show you how to use regular expressions to remove all non-digits characters of a String and return the number only String in Java application.