AmountParser.java

package gk;

import static java.math.BigDecimal.ZERO;

import java.math.BigDecimal;
import java.util.Scanner;

public class AmountParser {

    Scanner sc = new Scanner(System.in);

    public static void main(String[] args) {
        var parser = new AmountParser();

        var value = parser.inputBigDecimalValue("> ", BigDecimal.ONE, BigDecimal.TEN);

        System.out.println("The selected value is " + value);
    }

    public BigDecimal inputBigDecimalValue(String prompt, BigDecimal min, BigDecimal max) {

        while (promptAndGetNextInput(prompt)) {
            String input = sc.nextLine();

            if (!isInputValid(input)) {
                System.out.println("Invalid input.");
                continue;
            }

            var amount = new BigDecimal(input);

            if (!isAmountInRange(amount, min, max)) {
                System.out.println("Input out of range from " + min + " to " + max);
                continue;
            }

            return amount;
        }

        return ZERO;
    }

    private boolean promptAndGetNextInput(String prompt) {
        System.out.print(prompt);
        return sc.hasNext();
    }

    private boolean isInputValid(String line) {
        try {
            new BigDecimal(line);
            return true;
        } catch (NumberFormatException nfe) {
            return false;
        }
    }

    private boolean isAmountInRange(BigDecimal amount, BigDecimal min, BigDecimal max) {
        return amount.compareTo(min) >= 0 && amount.compareTo(max) <= 0;
    }
}