How do I enter a new line in a cell in Google Sheets? When accessing a spreadsheet in Google Drive on a computer with a keyboard, I can enter a new line in a single cell by pressing alt+enter.

My keyboard on my Android doesn't even have an alt key.

How do I enter a new line on my Android device?

For a keyboard on my Android, I'm currently using Swype, but I am assuming, and hoping, there is some kind of general approach that is not specific to a particular keyboard.
Easiest way:  add an extra letter at the end of the line. Select that letter. Hit enter. The letter will be replaced with a new line.