import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Main {
public static void main(String[] argv) throws Exception {
// 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();
// Try a different input
matcher.reset("b");
matchFound = matcher.matches();
// Determine if pattern matches beginning of input
matchFound = matcher.lookingAt();
}
}