View JAR Source in IntelliJ IDEA | Generated by AI
In IntelliJ IDEA, you can easily view the source code of a JAR file. There are a few approaches depending on whether the JAR contains source files or just compiled .class files:
1. Open the JAR in IDEA
- Go to File > Open…
- Select the JAR file.
- IDEA will open it in the Project view like a regular archive.
- If the JAR contains
.javasource files, you can browse them directly. - If it contains only
.classfiles, IDEA will decompile them automatically into readable Java code.
2. Attach Sources to a Library JAR
If the JAR is part of a library (like Maven or Gradle dependencies):
- Go to File > Project Structure > Libraries (or Modules > Dependencies if it’s module-specific).
- Select the JAR.
- Click Attach Sources… and point IDEA to the
-sources.jar(if available). - Now IDEA will show the real source instead of just decompiled bytecode.
3. Quick Navigation
- Hold Ctrl (Cmd on macOS) and click a class or method that comes from the JAR.
- If no sources are attached, IDEA shows the decompiled version.
- If sources are attached, you’ll see the original Java code.
4. External Decompiler Plugins (Optional)
IDEA already has a built-in decompiler, but you can install plugins like Fernflower or CFR if you want alternative decompilation.
👉 Usually, if it’s a dependency managed by Maven/Gradle, IDEA can automatically download and attach the -sources.jar from the repository. If it’s a standalone JAR, you’ll need to attach sources manually or rely on the decompiler.
Do you want me to also explain how to extract the JAR’s source code outside IDEA (using tools like jd-gui or jar xf), or do you mainly want to stick to working inside IDEA?