Run on Simulator

In order to execute an Application on the Simulator, the SDK provides the Gradle runOnSimulator task. The prerequisites of this task are:

  • The Application main class or Feature class must be configured, as described in Configure a Project.
  • If the Application has a main class, the target VEE Port must be defined. Refer to the Select a VEE Port page to know the different ways to provide a VEE Port for a module project.
  • If the Application has a Feature class and a .kf file containing the property entryPoint set to the Full Qualified Name of the Feature class in the src/main/resources folder , the target Kernel must be defined. Refer to the Select a Kernel page to know the different ways to provide a Kernel for a module project.

Once these prerequisites are fulfilled, the Application can be started with the Simulator:

By double-clicking on the runOnSimulator task in the Gradle tasks view:


With a simple Hello World Application, the output should be:

=============== [ Initialization Stage ] ===============
=============== [ Converting fonts ] ===============
=============== [ Converting images ] ===============
=============== [ Launching on Simulator ] ===============
Hello World!
=============== [ Completed Successfully ] ===============



The execution of the runOnSimulator task can fail if the SDK EULA has not been accepted. In that case, you can set the ACCEPT_MICROEJ_SDK_EULA_V3_1B environment variable to YES and restart your IDE or you can define the accept-microej-sdk-eula-v3-1b System property by creating a custom configuration. For more information about SDK EULA, refer to the Licenses chapter.

Verbose Mode

If you need more information about the execution of the Application with the Simulator, the verbose mode can be enabled by using the --info Gradle option:

./gradlew runOnSimulator --info

Debug on Simulator

The SDK allows to run an Application with the Simulator in debug mode by setting the System property debug.mode to true when executing the runOnSimulator task:

./gradlew runOnSimulator -P"debug.mode"=true

The debug mode is activated on the port 12000 by default. The port can be changed by using the System Property debug.port:

./gradlew runOnSimulator -P"debug.mode"=true -P"debug.port"=8000

Once started, the Simulator waits for the connection of a debugger.

If you want to connect the IDE debugger:


Android Studio and IntelliJ IDEA need an Architecture 8.1 or higher for debug mode.

  • Add a breakpoint in your Application code.
  • Click on Run > Edit Configurations....
  • Click on + button (Add New Configuration).
  • Select Remote JVM Debug.
  • Click on the New launch configuration button.
  • Give a name to the launcher in the Name field.
  • Set the debug host and port.
  • Click on the Debug button.

The debugger should connect to the Simulator and you should be able to debug your Application.

Generate Code Coverage

To generate the Code Coverage files (.cc), invoke the :runOnSimulator task as follow:

gradle :runOnSimulator -D"" -D""

Option Name:


It specifies the period between the generation of .cc files.


If the application is abruptly ended (for example with Ctrl-C) before the the first period, no .cc files are generated.

Option Name:


Set to true to enable the generation of Code Coverage files, don’t define the property to disable the generation.

Generate Heap Dump

Option Name: s3.inspect.heap


Set to true to enable a dump of the heap each time the System.gc() method is called by the MicroEJ Application. The .heap files are generated in build/output/application/heapDump/.

Use the Heap Viewer to visualize the .heap files.