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Text lesson

replaceAll()

Example

Substitute each instance of a regular expression match with a designated 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”));

ionMatches(int offset, String other, int otherOffset, int length)

Definition and Usage

The replaceAll() method in Java replaces every match of a regular expression within a string with a new substring.

Replacement strings may include a backreference denoted as $n, where n represents the index of a group in the pattern. Within the resulting string, occurrences of $n will be substituted with the substring matched by the corresponding group. If $0 is employed, it will be substituted with the entire expression. Refer to “More Examples” below for an illustration of using a backreference.

Suggestion: Consult the Java RegEx tutorial to gain insights into regular expressions.

Syntax

public String replaceAll(String regex, String replacement)

Parameter Values

Parameter	Description
regex	Mandatory. A regular expression that specifies the substrings to be searched for.
replacement	Necessary. The substring that will substitute each match.

Technical Details

REturns	A duplicate of the string where matches of the regular expression have been substituted with new substrings.
Throws	PatternSyntaxException occurs if the syntax of the regular expression is incorrect.
Java Version	1.4

More Examples

Example

Utilize a backreference to enclose numbers within parentheses.

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