Question

Say there is a sentence

That Sam-I-am

Two words end in the same sequence “am”, where the second sequence is the last word.

I need to write a regular expression to match such a sentence, where the sequence could be any string of letters.

The language is Java. What I don’t quite understand is how one would match something within a sentence and ignore the rest.

It is a prep question for a Java test.

Thank you.

This is code I’m using to test

public static void doMatching(){

    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

    try {

        String pattern, s;
        System.out.print("Pattern: ");
        pattern = in.readLine();
        while (!pattern.equals("quit")){
            System.out.print("String: ");
            s = in.readLine();
            System.out.println(Pattern.matches(pattern, s));
            System.out.print("Pattern: ");
            pattern = in.readLine();
        }
        } catch (IOException e){
            System.out.println("Error!");
    } catch (Exception e2){
        System.out.println("Unknown!");
    }

}


public static void main(String[] args) {
    // TODO code application logic here

    doMatching();
}

And here is the result

Pattern: (\\w+\\b).*\\b\\1$
String: that sam-i-am
false

Answer 1

"(\\w+\\b).*\\b\\1$"

That will match some non-trivial number of word characters at the end of a word(\\w+\\b) and ensure that they match at the end of the string as a complete word.