java regex for four connect row

Question

Suppose I have a row in four connect where X is player 1, _ is an empty slot and O is player two. Te row looks like this

X_X_XXXO

I want to check for these patterns

String patternString = "XXX_|XX_X|X_XX|_XXX";

this returns only one match : X_XX but I also want _XXX to return;

How should I expand my patternstring?

thank you

String text    = "X_X_XXXO";
String patternString = "XXX_|XX_X|X_XX|_XXX";
Pattern pattern = Pattern.compile(patternString);
Matcher matcher = pattern.matcher(text);

while(matcher.find()) {
  .. code
}