Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression

/
/
gm

Test String

Substitution

Processing...

Code Generator

Generated Code

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "(^\\w.*\\n\\n)+(^(##.*\\n)+)"; final String string = "tab_bar_edge top\n\n" + "## Which edge to show the tab bar on, top or bottom\n\n" + "tab_bar_margin_width 0.0\n\n" + "## The margin to the left and right of the tab bar (in pts)\n\n" + "tab_bar_margin_height 0.0 0.0\n\n" + "## The margin above and below the tab bar (in pts). The first number\n" + "## is the margin between the edge of the OS Window and the tab bar and\n" + "## the second number is the margin between the tab bar and the\n" + "## contents of the current tab.\n\n" + "tab_bar_style fade\n\n" + "## The tab bar style, can be one of:\n" + "## \n" + "## fade\n" + "## Each tab's edges fade into the background color (see tab_fade)\n" + "## slant\n" + "## Tabs look like the tabs in a physical file\n" + "## separator\n" + "## Tabs are separated by a configurable separator (see tab_separator)\n" + "## powerline\n" + "## Tabs are shown as a continuous line with \"fancy\" separators\n" + "## (see tab_powerline_style)\n" + "## custom\n" + "## A user-supplied Python function called draw_tab is loaded from the file\n" + "## tab_bar.py in the kitty config directory. For examples of how to\n" + "## write such a function, see the functions named draw_tab_with_* in\n" + "## kitty's source code: kitty/tab_bar.py. See also\n" + "## this discussion https://github.com/kovidgoyal/kitty/discussions/4447\n" + "## for examples from kitty users.\n" + "## hidden\n" + "## The tab bar is hidden. If you use this, you might want to create a\n" + "## mapping for the https://sw.kovidgoyal.net/kitty/actions/#select-tab\n" + "## action which presents you with a list of tabs and allows for easy\n" + "## switching to a tab.\n\n" + "tab_bar_align left\n\n" + "## The horizontal alignment of the tab bar, can be one of: left,\n" + "## center, or right.\n\n" + "tab_bar_min_tabs 2\n\n" + "## The minimum number of tabs that must exist before the tab bar is\n" + "## shown\n\n" + "tab_switch_strategy previous\n\n" + "## The algorithm to use when switching to a tab when the current tab\n" + "## is closed. The default of previous will switch to the last used\n" + "## tab. A value of left will switch to the tab to the left of the\n" + "## closed tab. A value of right will switch to the tab to the right of\n" + "## the closed tab. A value of last will switch to the right-most tab.\n\n" + "tab_fade 0.25 0.5 0.75 1\n\n" + "## Control how each tab fades into the background when using fade for\n" + "## the tab_bar_style. Each number is an alpha (between zero and one)\n" + "## that controls how much the corresponding cell fades into the\n" + "## background, with zero being no fade and one being full fade. You\n" + "## can change the number of cells used by adding/removing entries to\n" + "## this list.\n\n" + "tab_separator \" ┇\"\n\n" + "## The separator between tabs in the tab bar when using separator as\n" + "## the tab_bar_style.\n\n" + "tab_powerline_style angled\n\n" + "## The powerline separator style between tabs in the tab bar when\n" + "## using powerline as the tab_bar_style, can be one of: angled,\n" + "## slanted, or round.\n\n" + "tab_activity_symbol none\n\n" + "## Some text or a unicode symbol to show on the tab if a window in the\n" + "## tab that does not have focus has some activity. If you want to use\n" + "## leading or trailing spaces surround the text with quotes. See\n" + "## tab_title_template for how this is rendered.\n\n" + "tab_title_template \"{fmt.fg.red}{bell_symbol}{activity_symbol}{fmt.fg.tab}{title}\"\n\n" + "## A template to render the tab title. The default just renders the\n" + "## title with optional symbols for bell and activity. If you wish to\n" + "## include the tab-index as well, use something like: {index}:\n" + "## {title}. Useful if you have shortcuts mapped for goto_tab N. If you\n" + "## prefer to see the index as a superscript, use {sup.index}. In\n" + "## addition you can use {layout_name} for the current layout name,\n" + "## {num_windows} for the number of windows in the tab and\n" + "## {num_window_groups} for the number of window groups (not counting\n" + "## overlay windows) in the tab. Note that formatting is done by\n" + "## Python's string formatting machinery, so you can use, for instance,\n" + "## {layout_name[:2].upper()} to show only the first two letters of the\n" + "## layout name, upper-cased. If you want to style the text, you can\n" + "## use styling directives, for example:\n" + "## {fmt.fg.red}red{fmt.fg.tab}normal{fmt.bg._00FF00}green\n" + "## bg{fmt.bg.tab}. Similarly, for bold and italic:\n" + "## {fmt.bold}bold{fmt.nobold}normal{fmt.italic}italic{fmt.noitalic}.\n" + "## Note that for backward compatibility, if {bell_symbol} or\n" + "## {activity_symbol} are not present in the template, they are\n" + "## prepended to it.\n\n" + "active_tab_title_template none\n\n" + "## Template to use for active tabs, if not specified falls back to\n" + "## tab_title_template.\n\n" + "xxxxxactive_tab_foreground #000\n" + "active_tab_background #eee\n" + "active_tab_font_style bold-italic\n" + "inactive_tab_foreground #444\n" + "yyyyinactive_tab_background #999\n" + "zzzzzinactive_tab_font_style normal\n\n" + "## Tab bar colors and styles\n\n" + "tab_bar_background none\n\n" + "## Background color for the tab bar. Defaults to using the terminal\n" + "## background color.\n\n" + "tab_bar_margin_color none\n\n" + "## Color for the tab bar margin area. Defaults to using the terminal\n" + "## background color.\n\n"; final String subst = "$2\\n$1"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE); final Matcher matcher = pattern.matcher(string); // The substituted value will be contained in the result variable final String result = matcher.replaceAll(subst); System.out.println("Substitution result: " + result); } }

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Java, please visit: https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html