StringReplaceAllWithNonRegex.md

Use of String#replaceAll with a first argument which is not a regular expression

Using String#replaceAll is less performant than String#replace when the first argument is not a regular expression.

Overview

The underlying implementation of String#replaceAll uses Pattern#compile and expects a regular expression as its first argument. However in cases where the argument could be represented by just a plain String that does not represent an interesting regular expression, a call to String#replace may be more performant as it does not need to compile the regular expression.

Recommendation

Use String#replace instead where a replaceAll call uses a trivial string as its first argument.

Example

public class Test {
    void f() {
        String s1 = "test";
        s1 = s1.replaceAll("t", "x"); // NON_COMPLIANT
        s1 = s1.replaceAll(".*", "x"); // COMPLIANT
    }
}

References

• Java SE Documentation: String.replaceAll.
• Common Weakness Enumeration: CWE-1176