<< Chapter < Page Chapter >> Page >

Print an uninitialized local variable

The statement in the following code fragment attempts to fetch and print a value using the uninitialized local variable named ref .

void doIt(){ char[]ref; System.out.print(ref);

As a result, the program refuses to compile, displaying the following error message under JDK 1.3.

Ap158.java:23: variable ref might not have been initialized System.out.print(ref);

Back to Question 8

Answer 7

See explanation below.

Explanation 7

The javadoc.exe program

When you download the JDK from Oracle, you receive a program named javadoc.exe in addition to several other programs.

The purpose of the javadoc program is to help you document the Java programs that you write. You create the documentation by running the javadoc program and specifying your source file or files as a command-line parameter. Forexample, you can generate documentation for this program by entering the following at the command line.

javadoc Ap157.java

Produces HTML files as output

This will produce a large number of related HTML files containing documentation for the class named Ap157 . The primary HTML file is named Ap157.html . A file named index.html is also created. This file can be opened in a browser to provide a viewer for all of theinformation contained in the many related HTML files.

(As a labor saving device, you can also specify a group of input files to the javadoc program, using wildcard characters as appropriate, to cause theprogram to produce documentation files for each of the input files in a single run.)

Special documentation comments and directives

If you include comments in your source code that begin with


and end with


they will be picked up by the javadoc program and become part of the documentation.

In addition to comments, you can also enter a variety of special directives to the javadoc program as shown in the following program.

public class Ap157{/** * Returns the character at the* specified index. An index ranges from *<code>0</code>to *<code>length() - 1</code>. ** @param index index of desired * character.* @return the desired character. */public char charAt(int index) { //Note, this method is not intended// to be operational. Rather, it // is intended solely to illustrate// the generation of javadoc // documentation for the parameter// and the return value. return 'a';//return dummy char}//end charAt method }//end class

The @param and @return directives

The @param and @return directives in the source code shown above are used by the javadoc program for documenting information about parameters passed to and information returned from the method named charAt . The method definition follows the special javadoc comment.

Back to Question 7

Answer 6


Explanation 6

Public classes in separate files

This program meets the requirement identified in Question 5 . In particular, this program defines two public classes. The source code for each public classis stored in a separate file. Thus, the program compiles and executes successfully, producing the text OK on the screen.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Object-oriented programming (oop) with java. OpenStax CNX. Jun 29, 2016 Download for free at https://legacy.cnx.org/content/col11441/1.201
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Object-oriented programming (oop) with java' conversation and receive update notifications?