Typecasting in Java or any other programming language for that matter, can thought of in this way. Consider pouring a big bucket full of water into a smaller empty bucket. Most of the water would probably fall down due to spillage. Similarly in Java, if you assign a "double" value into an "integer", there could be loss of data or error. Thus such an assignment needs typecasting.
Whereas when you pour water from a small bucket into a bigger empty one, all the water would easily fill into the bucket. Just the same way, an "integer" value can be assigned into a "double" without the need for an explicit typecasting.
Hope this explanation is simple enough for novices in Programming to understand.
