Java and Project Delivery

E&CE 250

Winter 2002

http://ece.uwaterloo.ca/~rrolon/java/tutorial.ppthttp://ece.uwaterloo.ca/~rrolon/java/tutorial.pdf

Java on Polaris• We are using the Java 2 Version 1.3 SDK

java -version

• It provides the following tools:

javac

java

javadoc

jar

jdb

appletviewer

The compiler for the Java programming language

The launcher for Java applications

API document generation

Creation and management of Java Archive files

The Java Debugger

The launcher for Java applets

Setting up1. Log onto Polaris

2. Open the MS-DOS prompt from Windows

3. Create a ece250 directory in n:\ n:\ mkdir ece250

4. Edit n:\privexec.bat and add the lines: set PATH=%PATH%;q:\eng\ece\jdk1.3\bin set CLASSPATH = N:\ece250

5. Run the batch file n:\privexec.bat again

Java program: StringOperations

• Use any text editor you like

• Enter the following program:

public class StringOperations {

public static void main (String[] args) {

String str = “If there were dreams to sell, What would you buy?”;

System.out.println (“The string is: ” + str);

System.out.println (“The length is: ” + str.length());

System.out.println (“Substring 14-20: ” + str.substring(14,20));

System.out.println (“Uppercase is: ” + str.toUpperCase());

}

}

• Save the program as StringOperations.java in your n:\ece250 directory

Compile the program• Open the MS-DOS prompt and change your directory:

n:\> cd ece250

• Now compile the program: n:\ece250> javac StringOperations.java

• If everything works, you’ll get no messages back

• Check to see if a StringOperations.class file has been created. n:\ece250> dir *.class

Note: For a Java program to compile properly, the name of the file and class defined must be the same. Remember: file name = class name.

Run the program• Now run the program:

n:\ece250> java StringOperationsIf it works, you’ll see:

The string is: If there were dreams to sell, What would you buy? The length is: 49

Substring 14-20: dreams

Uppercase is: IF THERE WERE DREAMS TO SELL, WHAT WOULD YOU BUY?

• If it fails, you’ll probably see:Exception in thread “main”java.lang.NoClassDefFoundError:StringOperations

This will happen if you forgot to set the classpath to include your working directory.

javadoc http://java.sun.com/j2se/1.3/docs/tooldocs/javadoc/

• A brief introduction to javadoc:– The purpose of this tool is to automatically generate

HTML documentation from your .java source files.

– You can run Javadoc on individual .java files, or .jar files

– A comment must be added before the section it is commenting

• The documentation is created by adding special tags in your .java files. These tags enable you to document your source code.

• The tags start with an "at" sign (@) and are case-sensitive (they must be typed with the lowercase letters as shown)

• Some common tags are: @author@version @exception @throws

javadoc

/** * The StringOperations class represents manipulation of strings * @author Ricardo Rolon * @version 1.0, Sep 2001 */

public class StringOperations { /** * Creates a String object. */

public static void main (String[] args) {

String str = “If there were dreams to sell, What would you buy?”;

System.out.println (“The string is: ” + str);

System.out.println (“The length is: “ + str.length());

System.out.println (“Substring 14-20: “+ str.substring(14,20));

System.out.println (“Uppercase is: “ + str.toUpperCase()); }

}

javadoc Example

Javadoc -author -version StringOperations.java

Jar files

http://www.javasoft.com/j2se/1.3/docs/tooldocs/win32/jar.html

• The jar tool allows you to create archives, similar to a .zip archive. (In fact, they are based on ZIP compression)

• There are several reasons we want to do this:– easier to transfer (compressed files = less time over a network)– easier to execute (all the .class files are in the .jar, makes only one

connection to the server)– jar’s can be signed by the author (security)– can store additional files like .html, readmes, etc.

Jar filesExample: jar cvmf myManifestFile myJarFile *.class *.html *.java

Where c option indicates that a jar file must be created,

v means to be Verbose m include my own Manifest file f put the .jar file in a separate File whose name is provided

The Java Virtual Machine needs to know which .class file in the .jar file contains the main( ) method. To do that, create a text file with just one line: Main-Class: <MainJavaClass>

For instance, in Project 1, if Rational.class is the class that contains main(), then MyManifestFile should contain the following line: Main-Class: Rational

Don’t forget to end the Main-Class line with a carriage return, otherwise jar will not recognize it.

jdb (java debugger)http://java.sun.com/j2se/1.3/docs/tooldocs/win32/jdb.html

• Compile the program with the -g option (extra class info)• Start jdb java debugger• Set breakpoints• Run program• Experiment with debugger commands:

– list -- Displays the source code of the line and several lines around it

– locals -- List the values of local variables that are currently in use

– print <item> -- Display the value of the variable, object, array

– step -- Executes the next line and stops again

– cont -- Continues running the program

– !! -- repeats the previous debugger command.

• After debugging the program, recompile the program without the -g option.

jdb --A debugging example

1. Compile the program: javac -g StringOperations.java

2. Start the debugger: jdb StrigOperations

3. Set breakpoints: stop in StringOperations.main stop at StringOperations:15

4. Run program: run StringOperations

5. Extract debugging info with commands: list, locals, print, step, cont

6. Recompile the program: javac StringOperations.java

Free Java Tools• JBuilder, Borland.

• VisualAge for Java, IBM.

• Forte for Java (http://www.sun.com/forte/ffj/),Sun Microsystems. JCreator, JEditor, etc.

• No native methods!!

Keep this in mind:

We have to be able to compile it and run it on the Java 2 SDK 1.3 platform

Vectorhttp://webobjects.uwaterloo.ca

• Vector is a web-based application course administration

• E&CE 250 will use Vector for the following:– Tracking of your marks for Projects– Electronic submission of your Projects

• Every student in this course has an account in Vector.

• Use your Polaris userid to login, and your ID # as your initial password.

• Change your password immediately.

Submitting files with Vector

• Project 1-3– individual submission, under studentID

• Project 4– group submission, under groupID

[even if group of one student]

Project 1-3: Naming of .jar files• Name the file as your numeric Student id

followed by pn where n is the project number. (That is, just 12345678p1.jar)

• In Vector, the file name will be prep ended by your Polaris account

• For example:If your Polaris userid is “student1” then this will upload the file as student1_12345678p1.jar

Project 4: Naming of .jar files• Send email to ece250 with group membership by signup due

date (even if group of 1). You will get your GroupID by email.

• Name the file as your GroupID followed by p4 where n is the project number. (If the GroupID is E250G007, use E250G007p4.jar)

• In Vector, the file name will be prepended by your GroupID

• For the above example, the file will be uploaded as E250G007_E250G007p4.jar

• Please post common questions on the ECE 250 newsgroup

• You can also send us email, phone us, or drop by during office hours

• Make sure you give yourself lots of time.

Recomendations