Error Handing, identifying offending string

[whytefish]

Was wondering if anyone knows any way to refer to the offending input string when handling a NumberFormatException error. Below is an example of the error i'm handling, I want to be able to include the "a" in the explanation.

Exception in thread "main" java.lang.NumberFormatException: For input string: "a"

Catch statement:

catch(java.lang.NumberFormatException e){
System.out.println("Input is not a Number, you entered" + (//want the "a" displayed here)
}

Thanks!

[Petr]

You shown a very short snippet. Can you show a full code?

[sunde887]

Is just displaying the full string incorrect? You can change it to something like "All items in the input must be numbers".

You can also probably get the offending item with indexOf, but it will take some thinking on your part.

[whytefish]

I'm just after a way to refer directly to a variable which contains a string rather than a double, and include it in the explanation. Thanks!

/**
	
	//convert strings to doubles
		try{
		Side1 = Double.parseDouble(Side1str);
		Side2 = Double.parseDouble(Side2str);
		Angle = Double.parseDouble(Anglestr);
		}
		catch(java.lang.NumberFormatException e){
			System.out.println("Input is not a Number")
		}
		EculidArea = AreaCalc();
	    System.out.println(EculidArea);
		}

[sunde887]

Try seeing what e.getMessage() returns. Im not exactly sure of the answer, but a quick search of the core API for number format exception found this method.

[garyiskidding]

You can add a

private boolean validDouble(String s)

method to your class, and keep using it to check for valid double valies. if the method returns false, you can tell the user that the input was'nt valid, along with that input.

I hope that's what you were looking for

[sunde887]

I just did a quick test of getMessage() and it returns for the input string: "offending string". You can either just print all of that, or just the string or just the incorrect letters.

To get just the string you could do something like

StringBuilder errorString = new StringBuilder(e.getMessage());
errorString.delete(0, 18);
System.out.println(errorString.toString());

[Petr]

see

package com.trackstudio.tools;

public class ParserNumber {
    /**
     * Method return case Number or null. it checks follows class Integer, Long, Float, Double
     * @param value value
     * @param cl Class for cast case
     * @param <T> Generic
     * @return return need value
     */
    public static <T extends Number> Number parseValueOrNull(String value, Class<T> cl) {
        try {
            if (value != null) {
                if (cl.equals(Integer.class)) {
                    return Integer.parseInt(value);
                } else if (cl.equals(Long.class)) {
                    return Long.parseLong(value);
                } else if (cl.equals(Float.class)) {
                    return Float.parseFloat(value);
                } else if (cl.equals(Double.class)) {
                    return Double.parseDouble(value);
                }
            }
        } catch (NumberFormatException e) {
            if (value != null && !value.isEmpty()) {
                System.out.println("NumberFormatException value - " + value + " cast case - " + cl.getSimpleName());
            }
            return null;
        }
        return null;
    }
}

[whytefish]

Thanks! That helps a lot, i'll look at that API in future.

[sunde887]

You are welcome, please mark your thread solved with the thread tools if you are done.