Can java.util.regex.Pattern do partial matches?

Question

Is it possible to know if a stream/string contains an input that could match a regular expression.

For example

 String input=\"AA\";         


        

Answer 1

Actually, you are in luck: Java's regex does have the method you want:

public boolean hitEnd()

Returns true if the end of input was hit by the search engine in the last match operation performed by this matcher.

When this method returns true, then it is possible that more input would have changed the result of the last search.

So in your case:

String input="AA";
Pattern pat=Pattern.compile("AAB");
Matcher matcher=pat.matcher(input);
System.out.println(matcher.matches()); // prints "false"
System.out.println(matcher.hitEnd());  // prints "true"