Hey there! I’ve been in your exact situation before—sticking to Java for a course while dealing with an IDE defaulting to Kotlin can be frustrating, but it’s totally fixable. Let’s walk through all the steps to get your setup aligned with your course requirements:

1. Set Java as the Default Language for New Projects #

This ensures every new project you create starts with Java files instead of Kotlin:

• Open Android Studio and go to File > Settings (Windows/Linux) or Android Studio > Preferences (Mac).
• The easiest way to lock in the default is via the new project wizard:
  • Start creating a new project, and on the "Configure your new project" screen, find the Language dropdown menu and select Java.
  • Look for the Save as default button at the bottom of this screen and click it. From now on, all new projects will default to Java.
• For extra assurance, check your file templates: Go to Settings > Editor > File and Code Templates, then under the Files tab, confirm templates like Activity Java and Application Class are set to generate Java code (not Kotlin).

2. Disable Automatic Java-to-Kotlin Code Conversion #

This stops the IDE from converting your copied Java code to Kotlin automatically:

• Go to Settings > Editor > General > Auto Import.
• Scroll down to the Kotlin section and uncheck the box labeled Convert Java code to Kotlin on paste.
• Click Apply then OK to save the change. Now when you paste Java code, it stays as Java.

3. Convert Existing Kotlin Files to Java (If Needed) #

If you already have a Kotlin project you want to switch to Java:

• Open the .kt file you want to convert.
• Go to Code > Convert Kotlin File to Java in the top menu.
• Note: The converted code might need minor tweaks (some Kotlin features don’t have direct Java equivalents), but for basic Android course content, this should work smoothly.

4. Verify Your Setup #

To make sure everything’s working:

• Create a new test project—your MainActivity should be a .java file, not .kt.
• Copy a snippet of Java code (like a basic onCreate method) into the editor and confirm it doesn’t get converted to Kotlin.

Quick Troubleshooting Tip #

If you run into any odd behavior (like the IDE still defaulting to Kotlin), try invalidating caches: Go to File > Invalidate Caches / Restart. This fixes a lot of random IDE glitches, especially in older versions like 3.0.1.

内容的提问来源于stack exchange，提问作者Ajiroghene