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  1. #1
    black_fender is offline Member
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    Nov 2012
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    Default Impose conditions to method parameters

    I have the main method that starts like this
    Java Code:
    public static void main(String[] args) { 
    //parameter evaluation
    byte TheDigit = Byte.parseByte(args[0]);
    I want to impose a condition to args[0] to be just a digit. I want to be able to display a WARN message if the value is not just a digit ( such as "-2" "99" "2,3" "word" etc). I want to avoid all those situations by displaying a warn message and exit the program. All this before the compiler shows me any error.
    For example if the method will be given the parameter "1.3" I dont want to let the compiler to display the error "java.lang.NumberFormatException: For input string: "1.3"
    I want to evaluate the parameter before that.
    In order to do that I have tried to create the variable this way :
    Java Code:
    byte TheDigit = (byte)args[0]
    by casting a byte variable from the input parameter but it does not work because args[0] is a string.
    Also I tried to parse the parameter as an integer and then to impose it the condition to be >= 0 and <= 9
    Java Code:
     int TheDigit = Integer.parseInt(args[1]);
    But it doesn't work if I give it "1.3" parameter because Integer.parseInt gives me the error "java.lang.NumberFormatException: For input string: "1.3" .

    Any ideas how to avoid all that ?


  2. #2
    PhHein's Avatar
    PhHein is offline Senior Member
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    Apr 2009
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    Default Re: Impose conditions to method parameters

    Java Code:
    if(args[0] == null || args[0].length() != 1 || !Character.isDigit(args[0].charAt(0))){
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