Java regular expressions meta characters

In Java regular expressions, metacharacters are special characters with a special meaning that are used to match or define patterns of text. Here are some of the most common metacharacters in Java regular expressions:

  1. . - The dot matches any character except line breaks.

  2. ^ - The caret is used to match the beginning of a line.

  3. $ - The dollar sign is used to match the end of a line.

  4. * - The asterisk matches zero or more occurrences of the preceding character or group.

  5. + - The plus sign matches one or more occurrences of the preceding character or group.

  6. ? - The question mark matches zero or one occurrence of the preceding character or group.

  7. | - The vertical bar is used to match either one alternative or another alternative.

  8. [] - Square brackets are used to create a character class that matches any character in the set of characters enclosed in the brackets.

  9. () - Parentheses are used to group expressions and capture them.

  10. {} - Curly braces are used to specify a specific number of occurrences of the preceding character or group.

  11. \ - The backslash is used to escape metacharacters, so they can be matched as normal characters.

These metacharacters can be combined in various ways to create powerful regular expressions that match very specific patterns in input strings. For example, the pattern ^abc.*def$ matches any string that starts with the characters "abc" and ends with the characters "def", with any number of characters in between.