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Exception Chaos Java Code Quiz

October 27, 2021

Working correctly with exceptions is crucial to a high-quality application that users enjoy using. This quiz reinforces some of the basic concepts of exceptions.

Therefore, what do you think will happen when running the following code?

import java.io.FileNotFoundException;

public class ExceptionChaosChallenge {
    static String s = "-";

    public static void main(String... doYouBest) {
        try {
            throw new IllegalArgumentException();
        } catch (Exception e) {
            try {
                try {
                    throw new FileNotFoundException();
                } catch (RuntimeException ex) {
                    s += "run";
                }
                throw new NullPointerException();
            } catch (Exception x) {
                s += "exc";
            } finally {
                s += "fin";
            }
        } finally {
            s += "of";
            try {
                throw new VirtualMachineError("JVMError") {};
            } catch (Error error) {
                s += "error" + error.getMessage();
            }
        }

        System.out.println(s);
    }

}

A) -runfinoferror

B) -excfinoferror

C) -runfinoferrorJVMError

D) -excfinoferrorJVMError

E) -runoferrorJVMError

Warning: Try to answer the correct alternative BEFORE seeing the answer! Only then will you refine your Java skills!

Working correctly with exceptions is crucial to a high-quality application that users enjoy using.

There are three main categories of exceptions:

  1. Checked Exceptions: used to handle a business requirement or something that is expected and the system can recover from the error.
  2. Unchecked Exceptions: used to handle non-functional errors and errors that can be avoided with an if such as ArrayOutOfBoundsException, NullPointerException... All of these exceptions inherit from RuntimeException.
  3. Error: Very serious errors that shouldn't be handled, instead we should fix the code.

Now that we know what are the main Exception/Error types, let's analyze the code, firstly an IllegalArgumentException will be thrown:

throw new IllegalArgumentException();

Then, the logic will go in the inner try statement. Then it will throw a new FileNotFoundException(). However, FileNotFoundException is not a RuntimeException, instead, it's an Exception.

Therefore, the code execution continues, and the next Exception that is thrown is NullPointerException. As NullPointerException is an Exception, we will concatenate"exc" in the s variable.

The finally clause should be always executed unless there is a System.exit(0) or some other edge-cases in the program. Therefore the next String to be concatenated is: "fin". The next finally clause will be also executed concatenating "of".

Inside the last finally clause we are throwing VirtualMachineError("JVMError"), therefore we will concatenate "error" and "JVMError" coming from this Error.

To conclude, the following String will be printed... what do you think?

If you have any questions about this Java Challenge, don’t hesitate to leave a question!

You can also check the original Java Challenge and take a look at the whole content of the Java Challengers initiative: https://javachallengers.com/exception-chaos-java-challenge/

Keep breaking your limits!

Author(s)

  • Rafael del Nero

    Java Champion, a passionate and creative developer who possesses strong technical knowledge and delivers solid systems focused on Spring and Java EE specifications for cloud applications. More than 10 years' ... Learn more

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