Java Video Tutorial 6

Java Video Tutorial 6In this part of my Java Video Tutorial I cover Java Exception handling. An exception is an object created when an error occurs.

I explain in this video the difference between run time and checked exceptions. I show you how to use try, catch and finally. We review the most common errors you will come across. I show you how to catch all and ignore individual exceptions. Yes, everything Java Exception wise will be covered.

If you missed part 1 watch it first here Java Video Tutorial.

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Code from Video

		/* An exception object is created when an error occurs
		 * It tells you what error occurred
		 * Here are many of the java exceptions
		 * java.lang.RuntimeException : exceptions that can be thrown during the normal 
		 * operation of the Java Virtual Machine. These exceptions are your responsibility 
		 * as a programmer
		 * ArithmeticException, ArrayStoreException, BufferOverflowException, 
		 * BufferUnderflowException, CannotRedoException, CannotUndoException, 
		 * ClassCastException, CMMException, ConcurrentModificationException, 
		 * DOMException, EmptyStackException, IllegalArgumentException, 
		 * IllegalMonitorStateException, IllegalPathStateException, 
		 * IllegalStateException, ImagingOpException, IndexOutOfBoundsException, 
		 * MissingResourceException, NegativeArraySizeException, NoSuchElementException, 
		 * NullPointerException, ProfileDataException, ProviderException, 
		 * RasterFormatException, SecurityException, SystemException, 
		 * UndeclaredThrowableException, UnmodifiableSetException, 
		 * UnsupportedOperationException
		 * java.lang.Exception : exceptions that are checked for by the java compiler
		 * AclNotFoundException, ActivationException, AlreadyBoundException, 
		 * ApplicationException, AWTException, BackingStoreException, 
		 * BadAttributeValueExpException, BadBinaryOpValueExpException, 
		 * BadLocationException, BadStringOperationException, 
		 * BrokenBarrierException, CertificateException, ClassNotFoundException, 
		 * CloneNotSupportedException, DataFormatException, 
		 * DatatypeConfigurationException, DestroyFailedException, 
		 * ExecutionException, ExpandVetoException, FontFormatException, 
		 * GeneralSecurityException, GSSException, IllegalAccessException, 
		 * IllegalClassFormatException, InstantiationException, 
		 * InterruptedException, IntrospectionException, 
		 * InvalidApplicationException, InvalidMidiDataException, 
		 * InvalidPreferencesFormatException, InvalidTargetObjectTypeException, 
		 * InvocationTargetException, IOException, JAXBException, JMException, 
		 * KeySelectorException, LastOwnerException, LineUnavailableException, 
		 * MarshalException, MidiUnavailableException, MimeTypeParseException, 
		 * MimeTypeParseException, NamingException, NoninvertibleTransformException, 
		 * NoSuchFieldException, NoSuchMethodException, NotBoundException, 
		 * NotOwnerException, ParseException, ParserConfigurationException, 
		 * PrinterException, PrintException, PrivilegedActionException, 
		 * PropertyVetoException, RefreshFailedException, RemarshalException, 
		 * RuntimeException, SAXException, ScriptException, ServerNotActiveException, 
		 * SOAPException, SQLException, TimeoutException, TooManyListenersException, 
		 * TransformerException, TransformException, UnmodifiableClassException, 
		 * UnsupportedAudioFileException, UnsupportedCallbackException, 
		 * UnsupportedFlavorException, UnsupportedLookAndFeelException, 
		 * URIReferenceException, URISyntaxException, UserException, XAException, 
		 * XMLParseException, XMLSignatureException, XMLStreamException, XPathException

		/* Common Exceptions
		 * ArithmeticException: An arithmetic operation occurs with no answer 
		 * (Division by Zero)
		 * ClassNotFoundException: A class is called for that doesn't exist
		 * IllegalArgumentException: A method has been passed an illegal argument
		 * IndexOutOfBoundsException: Thrown when an index for an array, string is
		 * called for, but doesn't exist
		 * InputMismatchException: (Part of NoSuchElementException) User enters the 
		 * wrong data type into a Scanner method
		 * IOException: An I/O operation failed
import java.util.Scanner; // Library that allows us to capture user input
import java.util.*; // Allows me to check for InputMismatchException
import*; // Allows for system input and output through data streams, serialization and the file system

public class LessonSix {
	// Creates a Scanner object that monitors keyboard input
	static Scanner userInput = new Scanner(;
	public static void main(String[] args){
		System.out.print("How old are you? ");
		int age = checkValidAge();
		if (age != 0){
		System.out.println("You are " + age + " years old");
	public static void divideByZero(int a)
			// The following throws an error because you can't divide by zero
			// Exception in thread "main" java.lang.ArithmeticException
		// If the exception ArithmeticException is thrown the following execute
		catch (ArithmeticException e)
			// Your custom error message
			System.out.println("You can't divide by zero");
			// Java's error message for this exception
			// Prints the exception name and error message
			// Prints the standard error stack trace
	public static int checkValidAge()
			return userInput.nextInt(); // nextInt() receives the user input
		catch (InputMismatchException e)
		{; // Skips the last user input and waits for the next
			System.out.print("That isn't a whole number");
			return 0;
	/* If you prefer to throw an exception to the calling method you use throw
	 * public static void getAFile(String fileName) throws IOException, FileNotFoundException
	 * {
	 * 		FileInputStream file = new FileInputStream(fileName);
	 * }
	 * If main called this method, main would have to handle the exception
	 * public static void main(String[] args) {
	 * 		try {
	 * 			getAFile("./somestuff.txt");
	 * 		}
	 * 		catch(IOException e) {
	 * 			System.out.println("An unknown IO Error Occured");
	 * 		}
	public static void getAFile(String fileName)
		/* If I tried to do this without providing for an exception
		* I'd get the error Unhandled Exception Type FileNotFoundException
		* A checked exception is an exception the compiler forces you to protect against
		FileInputStream file = new FileInputStream(fileName); 
		catch (FileNotFoundException e)
			System.out.println("Sorry I couldn't find that file");
		// You can catch numerous exceptions (List most specific first
		catch (IOException e) // Catches any IO Exception
			System.out.println("An unknown IO Error Occured");
		/* To ignore an exception do this
		 * catch (ClassNotFoundException e)
		 * {}
		/* Java 7 allows you to catch multiple exceptions at once
		 * catch (FileNotFoundException | IOException e)
		 * {}
		// This will catch any exception (This should always be last)
		catch (Exception e)
			System.out.println("I catch every exception");
		// If used finally is always executed whether there was an exception or not
		// It is used for clean up work like closing files and database connections

19 Responses to “Java Video Tutorial 6”

  1. Anonymous says:

    Awesome and educative videos!! Thanks a lot!
    Please upload the remaining videos soon.
    Looking forward to be good at Java. Thanks to You!

  2. Kishore says:

    Awesome and educative videos!! Thanks a lot!
    Please upload the remaining videos soon.
    Looking forward to be good at Java. Thanks to You!

  3. lakhan says:

    difference b/w throw and throws

  4. Tillman says:

    I like the way you explain the try and catch. Good Job, now I have a better understanding and I can practice it now.

  5. Jure says:

    You are the best! Thank you for this great series! 🙂

  6. Anonymous says:

    Thank you for making these videos…It helps a lot…God Bless you.

  7. Jimmy says:

    Why would you want to throws the exception up to the main instead of handling it where it happened in the method? What benefit is there in forcing it to be dealt with up in the main? I am just very confused about this and my professor’s explanation is very confusing.
    Thank you, great job with the videos.

  8. Anonymous says:

    Hey nice tutorials. Do you have an Eclipse debugging tutorial video?

  9. sean says:

    good lesson thanks very much.

  10. Anonymous says:

    I am a masters student in France and a beginner in programming.Just found ur series & have to admit that u r an excellent programmer and perfect mentor. Well done and thanks a bunch for sharing ur knowlege for free.

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