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

Language

Generated Code

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "(public|protected|private|static|\\s) +[\\w\\<\\>\\[\\]]+\\s+(\\w+) *\\([^\\)]*\\)\\s*(\\{)"; final String string = "/*\n" + " * Licensed to the Apache Software Foundation (ASF) under one or more\n" + " * contributor license agreements. See the NOTICE file distributed with\n" + " * this work for additional information regarding copyright ownership.\n" + " * The ASF licenses this file to You under the Apache License, Version 2.0\n" + " * (the \"License\"); you may not use this file except in compliance with\n" + " * the License. You may obtain a copy of the License at\n" + " *\n" + " * http://www.apache.org/licenses/LICENSE-2.0\n" + " *\n" + " * Unless required by applicable law or agreed to in writing, software\n" + " * distributed under the License is distributed on an \"AS IS\" BASIS,\n" + " * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\n" + " * See the License for the specific language governing permissions and\n" + " * limitations under the License.\n" + " */\n" + "package org.apache.pdfbox.pdmodel.interactive.documentnavigation.outline;\n\n" + "import org.apache.pdfbox.cos.COSDictionary;\n" + "import org.apache.pdfbox.cos.COSName;\n\n" + "/**\n" + " * This represents an outline in a pdf document.\n" + " *\n" + " * @author <a href=\"mailto:ben@benlitchfield.com\">Ben Litchfield</a>\n" + " * @version $Revision: 1.2 $\n" + " */\n" + "public final class PDDocumentOutline extends PDOutlineNode\n" + "{\n\n" + " \n" + " static java.io.BufferedWriter bfn;\n" + " static java.io.BufferedWriter bf;\n\n" + " /**\n" + " * Default Constructor.\n" + " */\n" + " public PDDocumentOutline()\n" + " {\n" + " \n" + " getCOSDictionary().setName(COSName.TYPE, COSName.OUTLINES.getName());\n" + " \n" + " }\n\n" + " /**\n" + " * Constructor for an existing document outline.\n" + " *\n" + " * @param dic The storage dictionary.\n" + " */\n" + " public PDDocumentOutline( COSDictionary dic )\n" + " {\n" + " super( dic );\n" + " getCOSDictionary().setName(COSName.TYPE, COSName.OUTLINES.getName());\n" + " }\n\n" + " @Override\n" + " public boolean isNodeOpen()\n" + " {\n" + " return true;\n" + " }\n\n" + " @Override\n" + " public void openNode()\n" + " {\n" + " // The root of the outline hierarchy is not an OutlineItem and cannot be opened or closed\n" + " }\n\n" + " @Override\n" + " public void closeNode()\n" + " {\n" + " // The root of the outline hierarchy is not an OutlineItem and cannot be opened or closed\n" + " }\n" + "}\n"; 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