I always get confused in data types i. e long,double...is there any solution

Answer 1

Adding to Taste answer :
int -> integers [ whole numbers( 1, 2 , 3 , ...) , 0 , -ve integers(-1, -2, -3 , ...)]

Answer 2

Lets make it simple
Float, Double -> decimal number
int -> whole number
long -> just like int, but can store long(er) value than int does

Answer 3

Taste Let me also add that doubles have "double" precision than floats

Answer 4

I would find a decent reference or make up your own list; print this out and keep it on hand when coding.