This tip shows the way to validate a string with respect to a regular expression. java.util.regex package is used for regular expression related operations.

In this example the input string (inputStr) is validated with the regular expression (rgString).

 import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class RegularExpExp {
    public static void main(String[] args) {
        String rgString = "write your regulat expression here";
        CharSequence inputStr = "write your input string that need to be validated";
        Pattern pattern = Pattern.compile(rgString);
        Matcher matcher = null;
        matcher = pattern.matcher(inputStr);
        if (matcher.matches()) {
        } else {
            System.out.println("Not Matched");