How to Escape Special Characters in Java Regex: A Complete Guide

Complete Guide to Escaping Special Characters in Java Regex

When utilizing regular expressions (regex) in Java, it's crucial to consider special characters that may interfere with your matching patterns. To ensure accurate matches, these characters must be escaped.

Special Characters to Escape

The following Java characters require escaping in regex:

• .[]{}()<>* =-!?^$|

Note that the closing brackets (] and }) only need escaping after opening the corresponding bracket. Additionally, characters like and - may work unescaped within [brackets] in certain cases.

Universal Escaping Solution

There is no universal solution for escaping all special characters in Java regex. However, you can employ a custom function to perform the escaping:

<code class="java">public static String escapeRegex(String input) {
    return input.replaceAll("([\.+*?^$|{}()\[\]])", "\\");
}</code>

Usage:

<code class="java">String pattern = "Sample [text]";
String escapedPattern = escapeRegex(pattern);
Pattern.compile(escapedPattern).matches("Sample [text]");</code>

By using this function, you can ensure that all special characters are escaped, ensuring accurate regex matching in the maximum possible cases.

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