validator.java

JAVA source code with book JAVA SE6

import java.util.Scanner;

public class Validator
{
	public static int getInt(Scanner sc, String prompt)
	{
		int i = 0;
		boolean isValid = false;
		while (isValid == false)
		{
			System.out.print(prompt);
			if (sc.hasNextInt())
			{
				i = sc.nextInt();
				isValid = true;
			}
			else
			{
				System.out.println("Error! Invalid integer value. Try again.");
			}
			sc.nextLine();  // discard any other data entered on the line
		}
		return i;
	}

	public static int getIntWithinRange(Scanner sc, String prompt,
	int min, int max)
	{
		int i = 0;
		boolean isValid = false;
		while (isValid == false)
		{
			i = getInt(sc, prompt);
			if (i <= min)
				System.out.println(
					"Error! Number must be greater than " + min);
			else if (i >= max)
				System.out.println(
					"Error! Number must be less than " + max);
			else
				isValid = true;
		}
		return i;
	}

	public static double getDouble(Scanner sc, String prompt)
	{
		double d = 0;
		boolean isValid = false;
		while (isValid == false)
		{
			System.out.print(prompt);
			if (sc.hasNextDouble())
			{
				d = sc.nextDouble();
				isValid = true;
			}
			else
			{
				System.out.println("Error! Invalid decimal value. Try again.");
			}
			sc.nextLine();  // discard any other data entered on the line
		}
		return d;
	}

	public static double getDoubleWithinRange(Scanner sc, String prompt,
	double min, double max)
	{
		double d = 0;
		boolean isValid = false;
		while (isValid == false)
		{
			d = getDouble(sc, prompt);
			if (d <= min)
				System.out.println(
					"Error! Number must be greater than " + min);
			else if (d >= max)
				System.out.println(
					"Error! Number must be less than " + max);
			else
				isValid = true;
		}
		return d;
	}

}