The String class’ .replaceAll() method replaces every matching subsequence in the input sequence with the specified replacement string.


string.replaceAll(String regex, String repl);

regex represents the regular expression: a set of special characters and letters used for matching specific text. repl represents the string to be substituted for each match.

Note: It’s important to note that certain characters in the replacement string, such as backslashes and dollar signs ($), may have special meanings, so it’s recommended to use Matcher.quoteReplacement(String) to prevent these characters from affecting the results.

Note: Both the .replace() and .replaceAll() methods replace all occurrences of a matching string and accept CharSequence as input. However, the key difference is that .replaceAll() treats the given CharSequence as a regular expression and searches for regex matches, while .replace() treats the input as plain text.


The example below removes all whitespace:

public class Main {
public static void main(String[] args) {
String myString = "Dog\t \r\rComputer\n\n \r House \t Yes \n ";
String regex = "\\s";
// The shorthand code \s represents spaces, tabs, and newline characters
String replacement = "";
String newString = myString.replaceAll(regex, replacement);

This results in the following output:



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