Debugging Sponge Within the IDE

Note

See Setting Up Your Workspace and Setting Up Your Project for more information about preparing your IDE and dependencies.

See the Running the Configuration section and the following Using the Debugger section on the Plugin Debugging page for more information on debugging with an IDE.

This article is currently based on IntelliJ. If you are an Eclipse user and feel like you can expand this article to include Eclipse, you can do so on our GitHub repository.

Using your IDE to debug Sponge is relatively straight-forward. For the most part, you import the build.gradle file into your IDE after you have Setup the Workspace. Ensure you have JDK 8 installed and specified in your IDE and import the project as a Gradle project, then you are ready to run the code and perform tests.

Key Settings

Here are some settings to check to help minimize any problems.

Gradle Plugin

Ensure the Gradle plugin is enabled. To do so, go to File -> Settings -> Plugins. Look for the Gradle plugin in the Installed tab and verify a checkmark next to the plugin’s name. If you do not see the Gradle plugin, search for it in the Marketplace tab and install it.

Project SDK

The project SDK should be 1.8.0_20 or higher. The project language level should be 8 - Lambdas, type annotations etc.

Run/Debug Configurations

The Gradle task genIntelliJRuns will create the Run/Debug configurations for you. Run ./gradlew genIntelliJRuns in the project’s root directory. Perform this task before launching the IDE. Or, you can restart your IDE or relaunch the project after you run it. You should see Minecraft Client and Minecraft Server listed as application configurations and SpongeForge [jar] and SpongeForge [clean] listed as Gradle configurations.

Coremods

Note

Coremods do not pertain to SpongeVanilla. See the Sponge Glossary for a definition of coremod.

Except for the Sponge coremod, Gradle or other automation tools provided by Sponge do not set up coremods in your project. As a result, you must add them manually. To do so, specify each coremod in a comma-separated list with the -Dfml.coreMods.load parameter in the VM options for your project. You can locate the VM options in the Run/Debug Configurations.

Tip

The Mixins section of Best Practices has a discussion on mixins, coremods, and other low-level definitions.

Debugging Mixin also discusses other useful VM options in the Output section.

Classpath

While in the Run/Debug Configurations window, verify the Use classpath of module: is populated. Click on the drop-down menu and select a module with _main in its name when it specifies <no module>.

Tip

When in doubt, select the project on which you are working. For example, select SpongeForge_main when working with SpongeForge or SpongeVanilla_main when working with SpongeVanilla.

Using Your IDE

Now with everything working, you can do all of the usual tasks when in your IDE, such as setting breakpoints, stepping through code, examining variables, and evaluating expressions. You can also utilize regular aspects of the game, such as commands and log output.

Debugging With Mods and Plugins

When debugging code with a mod or plugin, place a copy of its jar file in the run/mods directory. The IDE will allow you to examine the code and set breakpoints. However, you must specify the directory as a library.

To do this, open Project Settings and select the Libraries project component. Click on + near the top of the middle column. Click on Java and navigate to the mods folder and select it. Click OK. You can now view source code and set breakpoints in the mods or plugins.

Warning

Be sure to comply with all copyright notices and license agreements when using this feature.