When I am in a .java file the unused code is usually grayed out or has a green underline saying this code will probably (probably because of some weird JNI/Reflection corner cases) be unused. But I have this project with thousands of Java files and I want to find ALL INSTANCES of such probable-unused codes. How can I do that in IntelliJ IDEA?
Just use Analyze | Inspect Code with appropriate inspection enabled (Unused declaration under Declaration redundancy group).
Using IntelliJ 11 CE you can now "Analyze | Run Inspection by Name ... | Unused declaration"
In latest IntelliJ versions, you should run it from Analyze->Run Inspection By Name:
Than, pick Unused declaration:
And finally, uncheck the Include test sources:
来源：https://stackoverflow.com/questions/6587729/how-to-use-intellij-idea-to-find-all-unused-code