How do I replace a key phrase only if it is a standalone word?

Question

For example, if I were to make the keyphrase "ball", then I would need the sentence "He caught the ball because he was playing baseball" to "He caught the XXXX because he was playing baseball". Instead, I'm getting "He caught the XXXX because he was playing baseXXXX". I'm using replaceAll, which is why I'm getting this error, but I was wondering if there is a way for me to check if there's a character that isn't whitespace afterwards, and only replace the word if there is either whitespace or special characters. The reason I'm struggling is because I still want the word to replaced if it is followed by a special character, but not a letter.

@marvin That doesn't satisfy the criteria; you'd need to use word boundaries, not a space. — Dave Newton, Jun 25 '17 at 17:34
See here: https://stackoverflow.com/questions/25738342/how-to-ensure-replaceall-will-replace-a-whole-word-and-not-a-substring — Florian S., Jun 25 '17 at 17:35

Marvin · Accepted Answer · 2017-06-25T17:48:51.277

You can use a boundary matcher (note that you have to escape the backslash). The word boundary \b also takes care of punctuation marks:

System.out.println("He caught the ball because he was playing baseball"
            .replaceAll("\\bball\\b", "XXXX"));
System.out.println("One ball, two cats. Two cats with a ball."
            .replaceAll("\\bball\\b", "XXXX"));
System.out.println("A ball? A ball!".replaceAll("\\bball\\b", "XXXX"));

Prints:

He caught the XXXX because he was playing baseball
One XXXX, two cats. Two cats with a XXXX.
A XXXX? A XXXX!

Firoz Memon · Answer 2 · 2017-06-25T18:44:43.570

Try this:

    String s = "He caught the ball because he was playing baseball";
    String replaceKey = "ball";
    String replaceValue = "XXXX";

    String[] sArray = s.split(" ");

    String finalS = "";
    for(int i=0; i<sArray.length;i++) {
        if(replaceKey.equals(sArray[i])){
            sArray[i] = replaceValue;
        }
    }

    System.out.println(String.join(" ", sArray));

OUTPUT: He caught the XXXX because he was playing baseball

EDIT:

    String s = "!ball! ?ball1 ball! ball1 ball, 1ball1 baseball ba.ll";
    String replaceKeyPattern = "^[\\W+[ball]\\W+]+$";
/*    \\W is all non word characters= special characters */

    String replaceKey = "ball";
    String replaceValue = "XXXX";

    String[] sArray = s.split(" ");

    String finalS = "";
    for(int i=0; i<sArray.length;i++) {
        if(sArray[i].matches(replaceKeyPattern)){
            sArray[i] = sArray[i].replace(replaceKey,replaceValue);
        }
    }

    System.out.println(String.join(" ", sArray));

OUTPUT:!XXXX! ?ball1 XXXX! ball1 XXXX, 1ball1 baseball ba.ll

Hope it helps!

What about the special characters as asked in OP: "I'm struggling is because I still want the word to replaced if it is followed by a special character, but not a letter." — Shailesh Saxena, Jun 25 '17 at 17:54

How do I replace a key phrase only if it is a standalone word?

2 Answers2