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

Substitution

Processing...

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 = "assertEquals\\(([^,]+),\\s(.+)\\);"; final String string = "package com.gdit.fwa.informant.model.definitions;\n\n" + "import static org.junit.Assert.assertEquals;\n\n" + "import org.junit.Test;\n\n" + "import com.gdit.fwa.informant.model.base.definition.RelationalOperator;\n" + "import com.gdit.fwa.informant.model.base.definition.SqlConstants;\n\n" + "@SuppressWarnings(\"static-method\")\n" + "public class RelationalOperatorTest {\n\n" + " @Test\n" + " public void testGetRelOperatorSql() {\n" + " assertEquals(RelationalOperator.DEFAULT.getRelOperatorSql(), \"\");\n" + " assertEquals(RelationalOperator.IS.getRelOperatorSql(), \"IS\");\n" + " assertEquals(RelationalOperator.IS_NOT.getRelOperatorSql(), \"IS NOT\");\n" + " assertEquals(RelationalOperator.EQUAL.getRelOperatorSql(), \"=\");\n" + " assertEquals(RelationalOperator.NOT_EQUAL.getRelOperatorSql(), \"<>\");\n" + " assertEquals(RelationalOperator.GREATER_THAN.getRelOperatorSql(), \">\");\n" + " assertEquals(RelationalOperator.LESS_THAN.getRelOperatorSql(), \"<\");\n" + " assertEquals(RelationalOperator.GREATER_EQUAL.getRelOperatorSql(), \">=\");\n" + " assertEquals(RelationalOperator.LESS_EQUAL.getRelOperatorSql(), \"<=\");\n" + " assertEquals(RelationalOperator.BETWEEN.getRelOperatorSql(), \"BETWEEN\");\n" + " assertEquals(RelationalOperator.IN.getRelOperatorSql(), \"IN\");\n" + " assertEquals(RelationalOperator.NOT_IN.getRelOperatorSql(), \"NOT IN\");\n" + " assertEquals(RelationalOperator.LIKE.getRelOperatorSql(), \"LIKE\");\n" + " assertEquals(RelationalOperator.NOT_LIKE.getRelOperatorSql(), \"NOT LIKE\");\n" + " assertEquals(RelationalOperator.SOUNDS_LIKE.getRelOperatorSql(), \"SOUNDS LIKE\");\n" + " }\n\n" + " @Test\n" + " public void testGetRelationalOperator() {\n" + " assertEquals(RelationalOperator.DEFAULT, RelationalOperator.getRelationalOperator(\"\"));\n" + " assertEquals(RelationalOperator.IS, RelationalOperator.getRelationalOperator(\"IS\"));\n" + " assertEquals(RelationalOperator.IS_NOT, RelationalOperator.getRelationalOperator(\"IS NOT\"));\n" + " assertEquals(RelationalOperator.EQUAL, RelationalOperator.getRelationalOperator(\"=\"));\n" + " assertEquals(RelationalOperator.NOT_EQUAL, RelationalOperator.getRelationalOperator(\"<>\"));\n" + " assertEquals(RelationalOperator.GREATER_THAN, RelationalOperator.getRelationalOperator(\">\"));\n" + " assertEquals(RelationalOperator.LESS_THAN, RelationalOperator.getRelationalOperator(\"<\"));\n" + " assertEquals(RelationalOperator.GREATER_EQUAL, RelationalOperator.getRelationalOperator(\">=\"));\n" + " assertEquals(RelationalOperator.LESS_EQUAL, RelationalOperator.getRelationalOperator(\"<=\"));\n" + " assertEquals(RelationalOperator.BETWEEN, RelationalOperator.getRelationalOperator(\"BETWEEN\"));\n" + " assertEquals(RelationalOperator.IN, RelationalOperator.getRelationalOperator(\"IN\"));\n" + " assertEquals(RelationalOperator.NOT_IN, RelationalOperator.getRelationalOperator(\"NOT IN\"));\n" + " assertEquals(RelationalOperator.LIKE, RelationalOperator.getRelationalOperator(\"LIKE\"));\n" + " assertEquals(RelationalOperator.NOT_LIKE, RelationalOperator.getRelationalOperator(\"NOT LIKE\"));\n" + " assertEquals(RelationalOperator.SOUNDS_LIKE, RelationalOperator.getRelationalOperator(\"SOUNDS LIKE\"));\n" + " }\n\n" + " @Test\n" + " public void testRelOpEqualityFunctions() {\n" + " for (RelationalOperator relOp : RelationalOperator.values()) {\n" + " if (relOp == RelationalOperator.IS || relOp == RelationalOperator.IS_NOT){\n" + " assertEquals(relOp.isEquality(), true);\n" + " assertEquals(relOp.getNullLogicOperator(), SqlConstants.OR);\n" + " assertEquals(relOp.getNullRelOperator(), RelationalOperator.IS);\n" + " assertEquals(relOp.getRelOperatorFilterSql(), RelationalOperator.IN.getRelOperatorSql());\n" + " } else {\n" + " assertEquals(relOp.isEquality(), false);\n" + " assertEquals(relOp.getNullLogicOperator(), SqlConstants.AND);\n" + " assertEquals(relOp.getNullRelOperator(), RelationalOperator.IS_NOT);\n" + " assertEquals(relOp.getRelOperatorFilterSql(), RelationalOperator.NOT_IN.getRelOperatorSql());\n" + " }\n" + " }\n" + " }\n\n" + " @Test\n" + " @SuppressWarnings(\"deprecation\")\n" + " public void testGetNullValue() {\n" + " assertEquals(RelationalOperator.getNullValue(), SqlConstants.NULL);\n" + " }\n\n" + " @Test\n" + " public void testGetNullClause() {\n" + " for (RelationalOperator relOp : RelationalOperator.values()) {\n" + " switch (relOp) {\n" + " case IS:\n" + " case EQUAL:\n" + " assertEquals(relOp.getNullClause(\"Test\"), \" OR Test IS null\");\n" + " break;\n" + " case IS_NOT:\n" + " case NOT_EQUAL:\n" + " assertEquals(relOp.getNullClause(\"Test\"), \" AND Test IS NOT null\");\n" + " break;\n" + " default:\n" + " assertEquals(relOp.getNullClause(\"Test\"), \"\");\n" + " }\n" + " }\n" + " }\n\n" + "}\n"; final String subst = "assertEquals\\($2\\, $1\\);"; final Pattern pattern = Pattern.compile(regex); 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