/*
 * This program shows two ways to validate input, specifically positive
 * integers.  
 */
package validateintmethod;

import java.util.Scanner;

/**
 *
 * @author jcmtiernan
 */
public class ValidateIntMethod
{

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args)
    {
        String intStrNum;
        Scanner in = new Scanner(System.in); 
        int intStr;
        boolean valid = true;          
        
        System.out.print("Please enter a positive integer. Your input will be validated: ");           
        intStrNum = in.next(); 
        in.nextLine();   
        intStr = validatePosInt(intStrNum);
        if (intStr != -1)
        {
            System.out.printf("You entered %d which is a positive integer. \n\n",intStr); 
        }  
        else
        {
            System.out.printf("You entered %s which is NOT a positive integer. \n\n",intStrNum);              
        }
        
        
        System.out.print("Please enter a positive integer. Your will be required to enter valid data: ");           
        intStrNum = in.next(); 
        in.nextLine();   
        intStr = requirePosInt(intStrNum);     
        System.out.printf("You entered %d which is a positive integer. \n\n",intStr); 
        
    }

    /** validatePosInt 
     *  Checks a given input string to determine if it contains a positive integer.
     *  If the input is positive, it is returned.  If the input is negative, -1 is 
     *  returned.
     */
    public static int validatePosInt(String intStrNum)   
    {
        int intStr;
        boolean valid;      

        valid = intStrNum.matches("\\d+");
        
        //intStrNum = intStrNum+"Val";

        if (valid)
        {    // This turns the digits of string intStrNum into an int
            int length = intStrNum.length();
            intStr = Integer.parseInt(intStrNum.substring(0,length));  
            //System.out.printf("You entered %s which is a positive integer. \n\n",intStrNum); 
            return intStr;
        }  
        else
        {
            //System.out.printf("You entered %s which is NOT a positive integer. \n\n",intStrNum);  
            return -1;
        }     
    }

    /** requirePosInt
     *  Checks a given input string and returns the positive integer entered by the user.
     *  If the input is not a positive integer, the user must enter a new value.  The 
     *  user must enter values until a positive integer is given.
    */
    public static int requirePosInt(String intStrNum)   
    {
        int intStr = -1;
        boolean valid;      
        Scanner in = new Scanner(System.in);     

        do
        {
            valid = intStrNum.matches("\\d+");     

            if (valid)
            {    // This turns the digits of string intStrNum into an int
                int length = intStrNum.length();
                intStr = Integer.parseInt(intStrNum.substring(0,length));  
                //System.out.printf("You entered %d which is a positive integer. \n\n",intStr); 
            }  
            else
            {
                System.out.printf("You entered %s which is NOT a positive integer. \n\n",intStrNum);  
                System.out.print("Please enter a positive integer: ");
                intStrNum = in.next(); 
                in.nextLine();  
                valid = false;
            }   
        }
        while(!valid);

        return intStr;

    }

}