Exception Handling - Java - page 512

Self-Test Exercises
30. How would the dialogue in Display 9.11 change if you were to omit the following
line from the catch block? (Try it and see.)

keyboard.nextLine();

31. Give the definition for the following method. Use the techniques given in Display
9.11.

/**
Precondition: keyboard is an object of the class Scanner that
has been set up for keyboard input (as we have been doing
right along). Returns: An int value entered at the keyboard.
If the user enters an incorrectly formed input she or he is
prompted to reenter the value,
*/
public static int getInt(Scanner keyboard)

ArrayIndexOutOfBoundsException
You should read Section 6.1 of Chapter 6, which covers array basics, before reading
this short subsection. If you have not yet covered some of Chapter 6, you can omit this
section and return to it at a later time.
If your program attempts to use an array index that is out of bounds, an Array-
IndexOutOfBoundsException is thrown and your program ends, unless the exception
is caught in a catch block. ArrayIndexOutOfBoundsException is a descendent of the
class RuntimeException and so need not be caught or accounted for in a throws
clause. This sort of exception normally indicates that there is something wrong with
your code and means that you need to fix your code, not catch an exception. Thus, an
ArrayIndexOutOfBoundsException normally functions more like a run-time error
message than a regular exception.
ArrayIndexOutOfBoundsException is in the standard Java package java.lang and
so requires no import statement should you decide to use it by name.

Chapter Summary
•

Exception handling allows you to design and code the normal case for your pro-
gram separately from the code that handles exceptional situations.

• An exception can be thrown in a try block. Alternatively, an exception can be

thrown in a method definition that does not include a try block (or does not
include a catch block to catch that type of exception). In this case, an invocation
of the method can be placed in a try block.