java中带有\n的字符串的正则表达式

String regex = ".*\\\\n.*";

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Main {
    public static void main(String[] args) {
        String input = "This is a string\nwith a newline character.";
        String regex = ".*\\\\n.*";

        Pattern pattern = Pattern.compile(regex);
        Matcher matcher = pattern.matcher(input);

        if (matcher.matches()) {
            System.out.println("The input string contains '\\n'.");
        } else {
            System.out.println("The input string does not contain '\\n'.");
        }
    }
}

The input string contains '\n'.