Assuming you chose IntelliJ as your Java IDE, and why wouldn't you?
There are a few tips I want to pass on for helping with code completion.
I assume you already know Ctrl+Space to start code completion.
In the code completion pop-up you can use Ctrl+Q to see the JavaDoc help for that method.
And if you get stuck with the parameters for a method then Ctrl+P can show you what options are available.