How to print stack trace in custom exception?

Question

I define a custom exception like so :

package source.exception;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class ValidationException extends Exception
{
    private static final Logger logger = LoggerFactory.getLogger("source.exception.ValidationException");

    public ValidationException(String message)
    {
        super(message);
        ValidationException e = new ValidationException();
        logger.error("Exception : {}" , e);
    }
}

In the main program I use this exception like so :

public void readFile(String path) throws ValidationException
    {
        logger.debug("Input file path = {}" , path);
        try
        {
            if(validatePath(path))
            {
                mathExpressionReader = new BufferedReader(new FileReader(path));
            }
            else
            {
                throw new ValidationException("Your file dose not exist!");
            }
        }
        catch(Exception ex)
        {
            logger.error("Exception {} has occurred" , ex);
        }
    }

Now I don't know how to print stack trace when validatePath fail(means if statement become false) .Can anyone help me to print stack trace in custom exception?

ValidationException e = new ValidationException(); logger.error("Exception : {}" , e); - what's this meant to do? — Stack Exchange Broke The Law
– Stack Exchange Broke The Law, Commented Sep 27, 2015 at 5:58
@ immibis yes.but when I define this statment in ValidationException class give me an error . In readFile() method I want to stop the running if validate Path is false and then print stack tarce in file with logback — marzie
– marzie, Commented Sep 27, 2015 at 6:04
Why are you logging in the exception constructor?! Maybe you mean logger.error("Error", this)? — George Simms
– George Simms, Commented Sep 27, 2015 at 6:33
@George Simms In readFile() method I want to stop the program running by define custom exception and throws in method body then print stack trace with logback but I don't know how to do this? — marzie
– marzie, Commented Sep 27, 2015 at 6:41

Hong Duan · Accepted Answer · 2015-09-27 07:18:31Z

3

Why not just using e.printStackTrace()?

public class ValidationException extends Exception
{
    public ValidationException(String message)
    {
        super(message);
    }
}

public void readFile(String path) throws ValidationException
{
    logger.debug("Input file path = {}" , path);
    try
    {
        if(validatePath(path))
        {
            mathExpressionReader = new BufferedReader(new FileReader(path));
        }
        else
        {
            throw new ValidationException("Your file dose not exist!");
        }
    } catch (ValidationException e) {
        // This will print the stack trace.
        e.printStackTrace();
    }
}

edited Sep 27, 2015 at 7:18

answered Sep 27, 2015 at 6:12

Hong Duan

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1 Comment

marzie Over a year ago

where do I use try block?In readFile() method?I am new in java .

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