// Compile regular expression String patternStr = "b"; Pattern pattern = Pattern.compile(patternStr); // Determine if there is an exact match CharSequence inputStr = "a b c"; Matcher matcher = pattern.matcher(inputStr); boolean matchFound = matcher.matches(); // false // Try a different input matcher.reset("b"); matchFound = matcher.matches(); // true // Determine if pattern matches beginning of input matchFound = matcher.lookingAt(); // false