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Thread: Basic String to Double Convertion Problem

  1. #1
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    Default Basic String to Double Convertion Problem

    I have no idea why I'm having so much trouble with this. It should be a very basic problem.

    Ok, so I have a GUI with a text box, where the user inputs a money amount (money is in USD). I need to convert the String amount to a double (I know I shouldn't use doubles for money, but I'm not working with "real" money, so it's not a big deal). I am attempting to create a method which can convert the String to a double, but I need to take into account the different inputs the user can do.
    My current scenarios are:
    #1: 503.21
    #2: $503.21
    #3: 503
    #4: $503
    Obviously, I need to be able to strip off the dollar sign before converting. The problem I am having is recognizing the dollar sign.
    The method I created to do the conversion is:
    public static double moneyToDouble(String s) {
    	s = s.trim();
    	String value = s.contains("\\$") ? s.replaceAll("\\$", "") : s;
    	return ValueChecker.getDoubleValue(value);
    }
    My unit tests fail for #2 and #4 (the ones with the dollar signs). The problem I am having is that the contains() method is always evaluating to false, so the $ is never replaced. I also tried with: s.contains("$"), which also failed.

    **For reference, the ValueChecker.getDoubleValue(String) method just does a normal Double.parseDouble(Strng), but defaults to 0 if the sent String is null or empty.**

    Does anyone have any advice for me?
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  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Basic String to Double Convertion Problem

    Would indexOf() work?
    If you don't understand my answer, don't ignore it, ask a question.

  3. #3
    Senior Member PhHein's Avatar
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    Default Re: Basic String to Double Convertion Problem

    contains(CharSequence) is not a regex.
    String value = s.contains("$") ? s.replaceAll("\\$", "") : s;

    BTW: you don't need the ternary operator. If "\\$" isn't a matching pattern, the replaceAll will do nothing.

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    Default Re: Basic String to Double Convertion Problem

    Arg, PhHein was right.
    His code snippet works. I knew it was something silly I was overlooking.
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