Parting shots

Keeping class files separate

Previously, we issued the following commands to compile and pre-verify our MIDlets:

javac -bootclasspath c:\j2me\midp1.0.3fcs\classes FirstMIDlet.java

preverify -classpath c:\j2me\midp1.0.3fcs\classes;. -d . FirstMIDlet

With this approach, the pre-verified class file overwrote the class file created by the compiler. For small applications, this is not much of an issue. However, as the complexity of your applications increase, so will the number of files that you need to juggle. One easy way to lend some organization is to place class files from the compiler and pre-verifier into separate directories.

Steps to separate class files:

#1 - Create new directories

Create directories with the names jclasses and pclasses.
These directories will hold the output from the compiler and pre-verifier, respectively.

#2 - Change command line syntax for compiler and pre-verifier

javac -bootclasspath c:\j2me\midp1.0.3fcs\classes -d jclasses *.java

preverify -classpath c:\j2me\midp1.0.3fcs\classes -d pclasses jclasses

-d jclasses informs the Java compiler to write the class files into the directory jclasses.
-d pclasses jclasses informs the pre-verifer to write the pre-verified class files into the directory pclasses. The reference to jclasses instructs the pre-verifier where to locate the class files to pre-verify.

#3 - Change command line for creating the JAR

jar cvfm MIDlets.jar manifest.txt -C pclasses . MIDlet1.png MIDlet2.png

-C pclasses . informs the JAR program to look in the directory pclasses and archive all (".") the files.

#4 - Load MIDlet suite

midp -classpath MIDlets.jar -Xdescriptor MIDlets.jad

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J2ME Wireless Toolkit

Sun Microsystems provides a free J2ME Wireless Toolkit to simplify the development cycle when writing MIDlets. The toolkit manages project directories, compiles, pre-verifies, and packages MIDlets (creates the JAR and JAD). The toolkit also provides several emulators to preview MIDlets.

Download J2ME Wireless Toolkit at http://java.sun.com/products/j2mewtoolkit.

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Table of contents

• Introduction
• The basics
• Downloading the software
• Installing and configuring
• Your first MIDlet
• The MIDlet suite
• Parting shots
• Resources
• About the author

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Local resources

• IBM Innovation Center - Austin, TX
• IBM Innovation Center - Chicago, IL
• IBM Innovation Center - Dallas, TX
• IBM Innovation Center - San Mateo, CA
• IBM Innovation Center - Waltham, MA
• Technical Briefings in North America

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