Android Studio "Open Declaration" like eclipse
Here are more details to help you avoid asking the same question for all the other commands:
Press Ctrl + Shift + A, and search for the command you're looking for ("declaration") for example. This finds the command "Declaration - Goto by Reference action - Ctrl + B".
So you just need to put your cursor on the method you want to go to, and press Ctrl + B? You can also Ctrl + Click to achieve the same goal.
The most useful keyboard shortcuts are described in the Help - Tip of the day dialog box. Read them all.
In IntelliJ-IDEA it's Right-Click => Go To => Declaration. As others noted, Android Studio is based on IntelliJ-IDEA and in most of the cases, the experience would be the same.
CTRL+B or
Right click, Go to -> Declaration
For Mac: CMD+B