Question

I understand Java regular expressions can be accessed from the String‘s matches convenience method, or going the long route and making a Pattern, etc. So, the following code should really print 2 “Yes!” lines to the output. It prints “Yes!” line and “no” line. What am I missing?

import java.util.regex.*;

public class TestRegex {
public static void main(String[] args) {
    String pattern = "html";
    String input   = "somehtml.txt";

    Pattern p = Pattern.compile(pattern);
    Matcher m = p.matcher(input);

    if(m.find()) {
        System.out.println("Yes!");
    }
    else {
        System.out.println("no");
    }

    if(input.matches(pattern)) {
        System.out.println("Yes!");
    }
    else {
        System.out.println("no");
    }

}

}

Output:

Yes!
no

Java version 1.6 on Win7 64-bit.

C:\Users\Michael Smith>java -version
java version “1.6.0_24”
Java(TM) SE Runtime Environment (build 1.6.0_24-b07)
Java HotSpot(TM) 64-Bit Server VM (build 19.1-b02, mixed mode)

Answer 1

matches() checks for the whole string matching the regular expression. find() only looks for a match somewhere in the string.