Java: How to only allow ints and commas in a string?

Question

I have written the following method to validate an input String and output it as an int array. The method works completely as I need it to but I would like to add some extra validation to it so that it only allows integers and commas in the input so there are no errors.

An example correct input would be:

"7,23,62,8,1130"

The method is:

public static int[] validator (String [] check) {

    int [] out = new int[5];

    try
    {
        if (0 < Integer.parseInt(check[0]) && Integer.parseInt(check[0]) < 100)
        {
            out[0] = Integer.parseInt(check[0]);
        }
        else
        {
            throw new InvalidMessageException();
        }
    }
    catch (InvalidMessageException ex)
    {
        System.err.println("Invalid instruction message");
        return null;
    }

    try
    {
        if (0 < Integer.parseInt(check[1]))
        {
            out[1] = Integer.parseInt(check[1]);
        }
        else
        {
            throw new InvalidMessageException();
        }
    }
    catch (InvalidMessageException ex)
    {
        System.err.println("Invalid instruction message");
        return null;
    }

    try
    {
        if(0 < Integer.parseInt(check[2]))
        {
            out[2] = Integer.parseInt(check[2]);
        }
        else
        {
            throw new InvalidMessageException();
        }
    }
    catch (InvalidMessageException ex)
    {
        System.err.println("Invalid instruction message");
        return null;
    }

    try
    {
        if (0 <= Integer.parseInt(check[3]) && Integer.parseInt(check[3]) < 256)
        {
            out[3] = Integer.parseInt(check[3]);
        }
        else
        {
            throw new InvalidMessageException();
        }
    }
    catch (InvalidMessageException ex)
    {
        System.err.println("Invalid instruction message");
        return null;
    }

    try
    {
        if(0 < Integer.parseInt(check[4]))
        {
            out[4] = Integer.parseInt(check[4]);
        }
        else
        {
            throw new InvalidMessageException();
        }
    }
    catch (InvalidMessageException ex)
    {
        System.err.println("Invalid instruction message");
        return null;
    }

    return out;

}

I have considered doing something like:

    inputText = inputText.replace(".", "");
    inputText = inputText.replace(":", "");
    inputText = inputText.replace(";", "");
    inputText = inputText.replace("\"", "");

etc... but it does not seem a particularly great solution. If anyone has a better idea, please let me know. Thanks very much for any help!

What about using Regular Expression ? Something like this ^(\d,)*\d$ would suits — Walfrat
– Walfrat, Commented Apr 8, 2016 at 14:49
I didn't fully understand what you want to do, Do you want to convert those values to int from a String input ? — Ducaz035
– Ducaz035, Commented Apr 8, 2016 at 14:49

Vampire · Accepted Answer · 2016-04-08 14:52:27Z

2

I'd say something like this should replace your method, without having read your code, just your requirements:

String input = "7,23,62,8,1130";
if (input.matches("(?:\\d+(?:,|$))+")) {
    int[] result = Arrays.stream(input.split(",")).mapToInt(Integer::parseInt).toArray();
} else {
    throw new InvalidMessageException("");
}

answered Apr 8, 2016 at 14:52

Vampire

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1 Comment

Alastair Warren Over a year ago

Thank you! This is what I was looking for.

Matteo Baldi · Accepted Answer · 2016-04-08 14:59:57Z

2

You can use a regex expression to validate your input:

[0-9]+(,[0-9]+)*,?

Check it with the String matches(regex) method as:

if (yourString.matches("[0-9]+(,[0-9]+)*,?")) {

}

edited Apr 8, 2016 at 14:59

answered Apr 8, 2016 at 14:50

Matteo Baldi

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Comments

Darth Android · Accepted Answer · 2016-04-08 14:51:53Z

0

This is exactly what regular expressions are for:

return inputText.matches("\\d+(,\\d+)*");

answered Apr 8, 2016 at 14:51

Darth Android

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