Android has support to input Emoji by typing the words that describe that emotion. But, by default this feature seems to be not installed and is hard to find.
To install and use it:
- Go to Settings > Language and input.
You must be able to see Google Keyboard here. Press the Settings icon to the right of it.
Go to Text correction > Add-on dictionaries > Emoji for English words. Press it and an Install button appears. Press it to install this dictionary.
Once installed, Emoji that is relevant to the words you are typing appear in the Suggestion bar above the keyboard. Click the Emoji to insert it.
Tried with: Android 4.4.4 and Moto G