Question

I’m writing a regexp in Java where I’m trying to find the bottom-margin in the css “margin:” shorthand property in a String and see if it’s negative.
The margin property can be specified with 1, 2, 3 or 4 values, end with px, em or % and the values might be negative and/or start with a dot. Values are separated with one or more white spaces in between. What is tried so far is a regexp like this:

//E.g. style may look like "... margin: 10px 2px" or "... margin: -.10em 1em 2em" etc.
public void findMargin(String style)
{
    Pattern compile = Pattern.compile("margin:\\s*(-?\\.?\\d+(?:em|px|%)\\s*){1,4}");
    Matcher matcher = compile.matcher(style);

    while (matcher.find())
    {
      .....
    }
}

I have problem to find the extract the bottom-margin property. Anyone have some input on how to achieve that?

Answer 1

This is the code I wrote to find the bottom-margin from the css margin shorthand property:

    Pattern compile1 = Pattern.compile("margin:\\s*((-?\\.?\\d+(?:em|px|%)\\s*){1,4})");
    Matcher matcher1 = compile1.matcher(style);

    if (matcher1.find())
    {
        String[] split = matcher1.group(1).trim().split("\\s+");
        String marginBottom;

        if (split.length < 3)
        {
            marginBottom = split[0];
        } else
        {
            marginBottom = split[2];
        }

        if (marginBottom.contains("-"))
        {
            System.err.println("Bottom margin is negative "  + marginBottom);
        }
    }