Setting up your IDE for use with Forge in 1.7.2

First, you open the IDE and select "Import Project...." from the main menu. If you have already opened a project you can either import directly from the "File" menu, or you can close the project first, also done through the "File" menu. Alternatively you can just open the project.

Next, you browse to your Forge directory and select the 'build.gradle' file, and hit "OK".

You can leave the next screen as-is and just hit OK. It might take a while to complete the import, but after that you'll be able to start developing your modification using Minecraft Forge and IntelliJ IDEA.

Note: To build your project's release version you'll still have to run gradle build.

First build the required project files for eclipse:

gradle eclipse

Next, open up Eclipse, and click "Switch Workspace" located in your "File" menu. This will populate your "eclipse" directory. Navigate to your Forge directory and select the "eclipse" folder.

You can now start development of your modification using Minecraft Forge inside the Eclipse IDE.

Note: To build your project's release version you'll still have to run gradle build.