| Handling Errors using Exceptions

## Specifying the Exceptions Thrown by a Method

> The previous section showed you how to write an exception handler for the `writeList()` method in the ListOfNumbers class. Sometimes, it's appropriate for your code to catch exceptions that can occur within it. In other cases, however, it's better to let a method further up the call stack handle the exception. For example, if you were providing the ListOfNumbers class as part of a package of classes, you probably couldn't anticipate the needs of all of the users of your package. In this case, it's better to not catch the exception and to allow someone further up the call stack to handle it.

> If the `writeList()` method doesn't catch the exceptions that can occur within it, then the `writeList()` method must specify that it can throw them. Let's modify the `writeList()` method to specify the methods that it can throw. To remind you, here's the original version of the `writeList()` method:

> >     public void writeList() {
> >         System.out.println("Entering try statement");
> >         int i;
> >         pStr = new PrintStream(
> >                   new BufferedOutputStream(
> >                      new FileOutputStream("OutFile.txt")));

> >         for (i = 0; i < size; i++)
> >             pStr.println("Value at: " + i + " = " + victor.elementAt(i));
> >     }

> As you recall, the `new FileOutputStream("OutFile.txt")` statement might throw an IOException (which is not a runtime exception). The `victor.elementAt(i)` statement can throw an ArrayIndexOutOfBoundsException (which, as a subclass of RuntimeException, is a runtime exception).

> To specify that `writeList()` throws these two exceptions, you add a `throws` clause to the method signature for the `writeList()` method. The `throws` clause is composed of the `throws` keyword followed by a comma-separated list of all the exceptions thrown by that method. The `throws` clause goes after the method name and argument list and before the curly bracket that defines the scope of the method. Here's an example:

> >     public void writeList() throws IOException, ArrayIndexOutOfBoundsException {

> Remember that ArrayIndexOutOfBoundsException is a runtime exception, so you don't have to specify it in the `throws` clause, although you can.

| Handling Errors using Exceptions