Exceptions - Java Software Solutions: Foundations of Program Design - page 557

The TestData program uses nested for loops to compute random values and
write them to the output file. After all values are printed, the file is closed. Output
files must be closed explicitly to ensure that the data is retained. In general, it is
good practice to close all file streams explicitly when they are no longer needed.

SELF-REVIEW QUESTIONS (see answers in Appendix N)
SR 11.13 What is a stream?

SR 11.14 What are the standard I/O streams?

SR 11.15 What Stream class object have we been using explicitly throughout

this topic?

SR 11.16 An I/O exception, the InputMismatchException , will occur during

the main method of the CreatingExceptions program (see Listing
11.5) if the user enters an alphabetic character. Why doesn't the
main method definition include a throws InputMismatchException
clause?

SR 11.17 An I/O exception, the FileNotFoundException , will occur during

the main method of the TestData program if the test.dat is not
writable. Why doesn't the main method definition include a throws
FileNotFoundException clause?

SR 11.18 What happens if the PrintWriter constructor of the TestDate class

is passed the fw object instead of the bw object?

11.7 Tool Tips and Mnemonics

Let's take a look at a some special features that can be used with any Swing com-
ponent. Appropriate application of these features can enhance the user interface
and facilitate the use of the components. This section describes the use of tool tips
and mnemonics, as well as the ability to disable components, then explores an
example that uses these features.
Any Swing component can be assigned a tool tip, which is
a short line of text that will appear when the cursor is rested
momentarily on top of the component. Tool tips are usually
used to inform the user about the component, such as the
purpose of a button.
A tool tip can be assigned using the setToolTipText method of a Swing com-
ponent. For example:
JButton button = new JButton ("Compute");
button.setToolTipText ("Calculates the area under the curve.");

KEY CONCEPT
Tool tips and mnemonics can
enhance the functionality of a
graphical user interface.