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
No Match

/
/
g

Test String

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 = "\\/\\*[^*]*\\*+(?:[^/*][^*]*\\*+)*\\/|\\/\\/.*"; final String string = "import android.content.res.Resources;\n" + " import android.os.Handler;\n" + " import android.preference.PreferenceFragment;\n" + " import android.view.ViewGroup;\n" + " * Provides the regex to identify domain HTTP(S) protocol and/or 'www' sub-domain.\n" + " *\n" + " * Used to format user-facing {@link String}'s in certain preferences.\n" + " */\n" + " public static final String ADDRESS_FORMAT_REGEX = \"^(https?://(w{3})?|www\\\\.)\";\n\n" + " /**\n" + " // Used to ensure that settings are only fetched once throughout the lifecycle of the fragment\n" + " private boolean mShouldFetch;\n\n" + " public View onCreateView(@NonNull LayoutInflater inflater,\n" + " ViewGroup container,\n" + " Bundle savedInstanceState) {\n" + " // use a wrapper to apply the Calypso theme\n" + " Context themer = new ContextThemeWrapper(getActivity(), R.style.Calypso_SiteSettingsTheme);\n" + " LayoutInflater localInflater = inflater.cloneInContext(themer);\n" + " View view = super.onCreateView(localInflater, container, savedInstanceState);\n\n" + " if (view != null) {\n" + " setupPreferenceList((ListView) view.findViewById(android.R.id.list), getResources());\n" + " }\n\n" + " return view;\n" + " }\n\n" + " @Override\n" + " public void onChildViewAdded(View parent, View child) {\n" + " if (child.getId() == android.R.id.title && child instanceof TextView) {\n" + " // style preference category title views\n" + " TextView title = (TextView) child;\n" + " WPPrefUtils.layoutAsBody2(title);\n" + " } else {\n" + " // style preference title views\n" + " TextView title = (TextView) child.findViewById(android.R.id.title);\n" + " if (title != null) WPPrefUtils.layoutAsSubhead(title);\n" + " }\n" + " }\n\n" + " @Override\n" + " public void onChildViewRemoved(View parent, View child) {\n" + " // NOP\n" + " }\n\n" + " @Override"; final Pattern pattern = Pattern.compile(regex); final Matcher matcher = pattern.matcher(string); while (matcher.find()) { System.out.println("Full match: " + matcher.group(0)); for (int i = 1; i <= matcher.groupCount(); i++) { System.out.println("Group " + i + ": " + matcher.group(i)); } } } }

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