Question

I have a Java program that processes one file at a time. This Java program is called from a wrapper script which logs the return code from the Java program. There are 2 types of errors. Expected errors and unexpected errors. In both cases I just need to log them.
My wrapper knows about 3 different states. 0-OK, 1-PROCESSING_FAILED, 2- ERROR.

Is this a valid approach?

Here is my approach:

enum ReturnCodes {OK,PROCESSING_FAILED,ERROR};

    public static void main(String[] args)
    {
        ...
            proc.processMyFile();
        ...
        System.exit(ReturnCodes.OK.ordinal());
    }
    catch (Throwable t)
    {
        ...
        System.exit(ReturnCodes.ERROR.ordinal());
    }


private void processMyFile()
{
    try
    {
        ...
    }catch( ExpectedException e)
    {
        ...
        System.exit(ReturnCodes.PROCESSING_FAILED.ordinal());
    }
}

Answer 1

The convention is to have

• Zero for success
• Positive numbers for warnings
• Negative numbers for errors

The history behind it is that error codes in some environments need to be an 8-bit value. For severe errors by convention the high bit is set (which effectively makes it -127 -> -1 for errors and 1 -> 127 for warnings)

Of course, ANSI-C 99 defines only two macros, EXIT_SUCCESS, which is 0 and EXIT_FAILURE which is some other number that is undefined in the spec.