Eclipse offers you a lot of shortcuts to work even more effectively. If you want to copy a line of code you can do this by using a simple combination of letters on your keyboard. Just be sure, that your cursor is in the line, which you want to copy. Then press Crtl + Alt + Down* and the line will be copied. You can also select a block of several lines and press the shortcut. All lines will be copied and pasted right in the next line after your selection.
To remove a line you can use the Crtl + D shortcut.
“Down” means the Arrow Down Key.