pattern matcher

import java.io.*;

import java.util.regex.*;

class pmatch

{

public static void main(String args[])throws IOException
    {

Pattern p=Pattern.compile("[0-9]{9}|[0-9]{8}|[0-9]{7}|[0-9]{6}");

System.out.println("Enter no.");

BufferedReader br=new BufferedReader (newInputStreamReader(System.in));

    String exp=br.readLine();
    Matcher m=p.matcher(exp);
   boolean b=m.matches();
    if(b==true)
    System.out.println("Valid number");
    else
    System.out.println("Invalid number");
    }
}

Here is a code that validates phone number.

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

public class ValidatePhoneNumber {
  public static boolean validatePhone(String phone) {
                return phone.matches("^[0-9]{6,9}$");
        }
    public static void main(String[] argv) {
      Scanner input = new Scanner(System.in);
      System.out.print("Enter Phone Number: ");
                String phone = input.nextLine();
                while (validatePhone(phone) != true) {
                        System.out.print("Invalid PhoneNumber!");
                        System.out.println();
                        System.out.print("Enter Phone Number: ");
                        phone = input.nextLine();
                }
        }
}