Is there a function like the \"open declaration\" in eclipse, that we can use in the new Android Studio?
Just like F3
button.
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.