how to move (up/down) code lines in android studio?

If you want the exact behavior of eclipse you can do this:

File --> Settings --> Keymap --> Code--> Folding--> assign Alt+↑/↓ to "Move Line Up/down" instead of "Move Statement up/down"

To move a line:

Place the caret at the line to be moved.

Do one of the following:

On the main menu, choose Code | Move Line Up or Code | Move Line Down.

Press Shift+Alt+Up or Shift+Alt+Down.