To run the MDK you have to install the Java Development Kit Version 1.3.1. For compatibility reasons with small PDAs that use Personal Java 3.1 you have to install Java Development Kit Version 1.1.8. also. You can download both versions from the java.sun.com/downloads.
In your development environment you can select the JDK version you want to use for building your project/application.
Select JDK in SAP NetWeaver Developer Studio
Use the Eclipse commands:
Window > Preferences > Java > Installed JREs
If you add JDK 1.1.8 as runtime to the Eclipse, make sure that you set "JRE type" (first option on the "add JRE" dialog window) to "Standard 1.1.x VM". Otherwise JDK 1.1.8 is not detected as valid JRE for Eclipse.
Select JDK in JBuilder
In JBuilder you can set the JDK version for each project individually.
New Project:
When you start a new project use the JBuilder commands:File > New Project
Follow the steps offered by the "New Project" wizard and you will find a dialog window in which you can select the path of the JDK version you want to use.
Existing Project:
Use the JBuilder commands:Project > Project Properties - select tab Paths
In the dialog window you can select the path of the JDK version you want to use.
To check or change the configuration of the different JDK versions, like the JDK home path, use the JBuilder commands:
Tools > Configure JDKs
The MDK Plugin or the JBuilder Wizard uses JDK 1.3.x to create the .war or .jar of your application. A PDA with Personal Java cannot read this format. You have to convert the .war or .jar file into a JDK 1.1.8 format before sending it to a PDA with Personal Java. To do that, unpack the .war or .jar file (using Winzip or WinCommander or another Unzip tool), maintaining the folder structure, into a temporary directory (for example: C:\TEMP). To use the JDK 1.1.8 package tool use following DOS box commands (we assume that you installed JDK 1.1.8 in folder JDK118):
Create a .jar File: cd\temp \jdk118\bin\jar cvfM myApplication.jar *.* Create a .war File: cd\temp \jdk118\bin\jar cvfM myApplication.war *.*