Is replaceAll a regex?

The difference between replace() and replaceAll() method is that the replace() method replaces all the occurrences of old char with new char while replaceAll() method replaces all the occurrences of old string with the new string .

The replaceAll() method replaces each substring of this string (the String on which it is called) that matches the given regular expression with the given replacement. It internally uses classes like Pattern and Matcher from java. util. regex package for searching and replacing matching characters or substring.

Java Regular Expressions are case-sensitive by default .

The indexOf() method returns the index number where the target string is first found or -1 if the target is not found. Like equals(), the indexOf() method is case-sensitive , so uppercase and lowercase chars are considered to be different.