com.pokercompany.stringcalc.StringCalculator.java Source code

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Here is the source code for com.pokercompany.stringcalc.StringCalculator.java

Source

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package com.pokercompany.stringcalc;

import java.util.Arrays;
import java.util.List;
import org.apache.commons.lang.StringUtils;

/**
 *
 * @author Horvth Dniel
 */
public class StringCalculator {

    private char separator = ',';

    public StringCalculator() {

    }

    public StringCalculator(char separator) {
        this.separator = separator;
    }

    public int add(String numbers) throws Exception {
        if (numbers == null) {
            throw new NullPointerException();
        }

        if (numbers.equals("")) {
            return 0;
        }

        if (!numbers.matches("-?[0-9]+([" + separator + "]-?[0-9]+)*[" + separator + "]?")) {
            throw new NumberFormatException("Bad character(s) in input string: " + numbers);
        }

        List<String> numbersList = Arrays.asList(numbers.split("(?<!\\" + separator + ")[" + separator + "]"));
        List<String> negativeNumbers = StringCalcUtil.getListWherePatternMatches(numbersList, "[-][0-9]+");

        if (negativeNumbers.size() > 0) {
            throw new Exception("Negative not allowed: " + StringUtils.join(negativeNumbers.iterator(), ","));
        }

        int sum = 0;
        for (String stringNumber : numbersList) {
            sum += Integer.valueOf(stringNumber);
        }

        return sum;
    }

    public char getSeparator() {
        return separator;
    }

    public void setSeparator(char separator) {
        this.separator = separator;
    }

}