如何使用IntelliJ IDEA查找所有未使用的代码?

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?When I am in a .java file the unused code is us