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How to use Eclipse with LeJosRT

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  1. Set up a project in Eclipse for your LeJosRT code. Click on File>New>Java Project.
  2. For project name enter something like LeJosRT. Click Next and then Finished. Eclipse creates a new folder for your LeJosRT code.
  3. Now we need to set the Eclipse classpath to the LeJosRT classes. In the Eclipse menus select Project>Properties and you will see a Properties window for your project. Select Java Build Path in the left hand frame and select the Libraries tab.
  4. Click on Add External Jars... and browse to the classes.jar file in the lib directory where you installed LeJosRT. Click OK.
  5. Now we need to set up the LeJosRT tools to compile and upload code to your NXT brick. Select Run>External Tools>External Tools Configurations... to bring up a new window. Select the Program item.
  6. We'll create the tool used for transferring code to the NXT. Type in the name NXT Download. For location browse to /LeJosRT/lejos_rt/bin/nxj. For working directories click Browse Workspace... and select the bin/ folder of your project (for example: LeJosRT code/bin). Finally in arguments type the following and click Apply : ${java_type_name}
  7. Select Run>External Tools>Organize Favorites...Click Add and add NXT Download tools. Click OK.

You can now compile and upload code to your NXT with Eclipse by adding a new File to your LeJosRT project (example :, writing your code and then clicking Run NXT Download.