How to move an object uniformly from one point to another at a fixed angle?

Question

In my 2d java game, I need to move projectiles from Enemy object to Player object in a straight line. I did some research and found out that I can use atan2(x, y) method of Math class to get the angle, but then how am i supposed to move the projectile in that particular angle(direction)? Any ideas would be very helpful.

Answer 1

The equation of movment with constant speed is simple

positionX = startPositionX + speedX * time 
positionY = startPositionX + speedY * time 

where

speedX = speed * sin(angle)
speedY = speed * cos(angle)

But most of the game use incremental aproach

posX = posX + speedX / lengthOfTick
posY = posY + speedY / lengthOfTick