CodeGym/Help with Java Tasks/Please help

Level 30

London

19.11.2019
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9comments

Please help

Question about the task

Resolved

I'm not actually sure what this code is doing, I've somehow managed to pass most of the requirements. I have no idea how to pass the last one though

1. Analyze the exceptions thrown by the BEAN.throwExceptions method.
2. The handleExceptions method must call the BEAN.throwExceptions method and handle exceptions:
2.1. if there is a FileSystemException, then log it (call the BEAN.log method) and rethrow
2.2. if there is a CharConversionException or any other IOException, then just log it (call the BEAN.log method)
3. Add to the handleExceptions method signature the exception class you throw in Item 2.1.
4. In the main method, handle the remaining exception by logging it. Use try-catch

Hint:
If you capture a MyException and you didn't want to catch it, you can rethrow it using code like:
catch (MyException e) { throw e; }

Requirements:

The handleExceptions method must call the BEAN.throwExceptions method.
The handleExceptions method should log the FileSystemException (call the BEAN.log method), and then rethrow it.
The handleExceptions method should only log (call the BEAN.log method) the CharConversionException.
The handleExceptions method should only log any IOException.
Add the FileSystemException class to the signature of the handleExceptions method.
The main method should use try-catch.
The main method should log the exceptions thrown by the handleExceptions method.

package com.codegym.task.task09.task0915; import java.io.CharConversionException; import java.io.IOException; import java.nio.file.FileSystemException; /* Catching custom exceptions */ public class Solution { public static StatelessBean BEAN = new StatelessBean(); public static void main(String[] args) throws FileSystemException, CharConversionException, IOException { try { handleExceptions(); } catch (FileSystemException e){ BEAN.log(e); throw e; } catch (CharConversionException e){ BEAN.log(e); } catch (IOException e){ BEAN.log(e); } } public static void handleExceptions() throws FileSystemException, CharConversionException, IOException { try { BEAN.throwExceptions(); } catch (FileSystemException e){ BEAN.log(e); throw e; } catch (CharConversionException e){ BEAN.log(e); } catch (IOException e){ BEAN.log(e); } } public static class StatelessBean { public void log(Exception exception) { System.out.println(exception.getMessage() + ", " + exception.getClass().getSimpleName()); } public void throwExceptions() throws CharConversionException, FileSystemException, IOException { int i = (int) (Math.random() * 3); if (i == 0) throw new CharConversionException(); if (i == 1) throw new FileSystemException(""); if (i == 2) throw new IOException(); } } }

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Guadalupe Gagnon

Level 37 , Tampa, United States

19 November 2019, 16:04

In this task the instructions call for you to code in 2 places: The first place, handleExceptions method, you need to: 1) throw exception 1a) catch FileSystemException, log it, then rethrow 1b) catch IOException and log it In the Main method: 1) handle the remaining exception by logging it Now there is only going to be one type of exception that can be thrown from the HandleException method, and this is the exception that should be caught in main. Foll the instructions on what to do with this exception and you will pass. Also remove the throws *Exceptions* that are not needed in the handleExceptions and main methods.

Anthony Chalk

Level 30 , London, United Kingdom

19 November 2019, 16:10

What remaining exception? If all the exceptions are dealt with in the handleExceptions method, why do we need to deal with them again in the main method?

Guadalupe Gagnon

Level 37 , Tampa, United States

19 November 2019, 16:18

There is one that is (re)thrown after logging

Anthony Chalk

Level 30 , London, United Kingdom

19 November 2019, 16:24

So I changed the main method to:

public static void main(String[] args) throws FileSystemException {
        try {
            handleExceptions();
        }
        catch (FileSystemException e){
            BEAN.log(e);

        }

    }

But, IntelliJ is telling me that I need to add a CharConversionException.

Guadalupe Gagnon

Level 37 , Tampa, United States

19 November 2019, 16:30

solution

sounds like you still have the throws CharConversionException on the handlesException method. It should look like this:

public static void handleExceptions() throws FileSystemException

Because the FileSystemException is the only one that will be thrown from this method.

Anthony Chalk

Level 30 , London, United Kingdom

19 November 2019, 16:35

Thank you

Guadalupe Gagnon

Level 37 , Tampa, United States

19 November 2019, 16:46

useful

a quick explanation: When you have throws *AnyExceptionType* as part of the method declaration, you are telling the compiler that this method is going to have that type of an exception that it can throw. Adding it here means that it is alerting the next level up (where the method is called from in code) that it needs to handle it. Of course, where it is called from in code could also add it to that method signature and pass it up again. If it is left uncaught at all points then it will eventually crash the program.

Anthony Chalk

Level 30 , London, United Kingdom

19 November 2019, 16:49

Okay, that makes it much clearer. So if you deal with an exception with a try-catch then you shouldn't throw it in the signature. Thank you so much for your help

Guadalupe Gagnon

Level 37 , Tampa, United States

19 November 2019, 17:37

Yes. That is the idea. You can still add it to the method if you REALLY want to after catching it (and not re-throwing it), but then you are telling the IDE that it needs to be caught up the chain even though it would never be thrown. Example: