Java Reference
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this.msgSize = 50, super.msgSize = 20
~~~~~~~ setErrorMsg in Diagnostic does this : ~~~~~~~
====== A serious error has occurred ======
Fri Apr 16 18:08:50 PDT 1999
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java.lang.Exception: Stack trace
at java.lang.Thread.dumpStack(Thread.java:983)
at Diagnostic.setErrorMsg(Diagnostic.java:27)
at HelloWorld.main(HelloWorld.java:69)
====== End of serious error message =====
R
EVIEWING THE
S
AMPLES
Let's review the changes you've made. Try to relate the sample source statements to
the result (for example, the output) each statement creates. If necessary, rerun the
samples or look at the complete source code for this exercise on the CD-ROM. Feel
free to experiment by yourself.
You first created a new class called
TextMessage
. You removed some of the data
members from
ErrorMsg
and placed them in
TextMessage
.
Since the data members
msgText
and
msgSize
now belong to
TextMessage
, you
defined a
setMsgText
method in
TextMessage
in order to set these variables.
You placed a new method named
getTranslation
in
TextMessage
. This method
examined the static variable named LANGUAGECODE.
The
ErrorMsg
class was adjusted to inherit from this new class. Since
ErrorMsg
in-
herits from
TextMessage
, the public members and methods in
TextMessage
are
automatically available to any class that creates an
ErrorMsg
class. In the exam-
ple, HelloWorld creates an instance of
ErrorMsg
and can access these variables as
if they are part of
ErrorMsg
.
ErrorMsg
and
TextMessage
share these variables.
When you set the static variable LANGUAGECODE to F, all instances of
TextMessage
simulated a translation into French. Instances of
ErrorMsg
(which
are inherited from
TextMessage
) also exhibit this behavior.
You created a new class
PrintfileErrorMsg
. It inherits from
ErrorMsg
.
