Java Regex Tester & Debugger FAQs

Q: How to match newline characters in Java regex?

Use `\n` to match a newline. If you want `.` to match newlines as well, enable DOTALL mode with `(?s)` or `Pattern.DOTALL`.

Question 1

Do I need to escape backslashes in Java regex?

Accepted Answer

Yes. In Java strings, a backslash is an escape character. To represent a literal backslash for a regex (like `\d`), you must write `\d`.

Question 2

How to use regex in Java?

Accepted Answer

Use `java.util.regex.Pattern` to compile your regex and `Matcher` to check against a string. Example: `Pattern.compile("foo").matcher("foobar").find()`.

Question 3

How to match newline characters in Java regex?

Accepted Answer

Use `
` to match a newline. If you want `.` to match newlines as well, enable DOTALL mode with `(?s)` or `Pattern.DOTALL`.

Question 4

What is the difference between matches() and find() in Java Matcher?

Accepted Answer

`matches()` attempts to match the *entire* region against the pattern. `find()` scans the input sequence looking for the *next* subsequence that matches the pattern.

Question 5

Does String.class have regex methods in Java?

Accepted Answer

Yes. `String.matches(regex)`, `String.split(regex)`, and `String.replaceAll(regex, repl)` all accept regular expressions directly.

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