This tutorial assumes you have already

• Read the Pre-requisites
• Downloaded the latest Forge MDK
• Setup your mod folder as described at the top of the main Forge 1.15.1 tutorials page
• Read and followed 1.0 - Gradle Configuration
• Chosen Eclipse from 1.1 - Importing the project into your IDE

Eclipse

1. Open up Eclipse and (if you aren’t already there) switch to your “workbench”.
   
2. Go to File > Import > Existing Gradle Project and import the project.
   
3. Wait for the import/sync to complete
   
   
   
4. Go to Gradle Tasks
   
5. Run the eclipse task
   This will take a while as Forge downloads everything and sets up your modding environment.
   
   
6. Run the genEclipseRuns task to generate the run configs to run minecraft
   
   
7. Refresh your project
   Go to your project explorer, select your project and then select refresh
   
8. Choose your run configuration
   Go to the Run Configurations menu
   
   Choose Java Application > runClient
   
   Open the Run menu and select the runClient run configuration
   
   All of these run configs launch minecraft.
   
   • runClient launches the minecraft client
   • runData launches minecraft in a special mode that only does the bare minimum required to automatically generate json files like recipes and blockstates.
   • runServer launches the minecraft server
9. Run the game
   
10. Change package representation to hierarchical (optional)
    
    

Troubleshooting

When asking for help make sure to include your console log.

If your run configs fail to generate:

First try closing eclipse, then running gradlew genEclipseRuns from the command line, then opening eclipse back up.
If this doesn’t work but the .launch files generate in your mod’s folder properly, try importing them manually.
Do this by going to File > Import > Launch Configurations, selecting your mods folder and importing all run configs from there.
Before:


After:

1.2 - Basic Mod