How would you write a character who is completely emotionless?

The character is an Android who is emotionless. I want to portray him properly but I am not sure, how? For example: <br><br>How he would react to situations <br>How would he interact with characters?<br>How he would speak <br>How he would think about things?<br>How he keeps himself busy? <br>How other characters react to him?<br>How he expresses himself?<br><br>Never wrote anything like this before.