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Java String replaceAll() Method

❮ String Methods


Example

Replace every match of a regular expression with a substring:

String myStr = "I love cats. Cats are very easy to love. Cats are very popular.";
String regex = "(?i)cat";
System.out.println(myStr.replaceAll(regex, "dog"));

Try it Yourself »


Definition and Usage

The replaceAll() method replaces the first match of a regular expression in a string with a new substring.

Replacement strings may contain a backreference in the form $n where n is the index of a group in the pattern. In the returned string, instances of $n will be replaced with the substring that was matched by the group or, if $0 is used, by the whole expression. See "More Examples" below for an example of using a backreference.

Tip: See the Java RegEx tutorial to learn about regular expressions.


Syntax

public String replaceAll(String regex, String replacement)

Parameter Values

Parameter Description
regex Required. A regular expression defining what substrings to search for.
replacement Required. The substring which will replace each match.

Technical Details

Returns: A copy of the string in which matches of the regular expression are replaced with new substrings.
Throws: PatternSyntaxException - If the syntax of the regular expression is incorrect.
Java version: 1.4

More Examples

Example

Use a backreference to wrap numbers in parentheses:

String myStr = "Quest complete! Earned 30 gold and 500 experience.";
String regex = "[0-9]+";
System.out.println(myStr.replaceAll(regex, "($0)"));

Try it Yourself »


❮ String Methods
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