Question

Why compiler doesn’t give error when we assign Integer(object) to int(primitive)?

int i;
Integer ii = new Integer(5);
i = ii;//no compilation error.

And this is the case with all other types(byte-Byte, float-Float)..

What is the reason? Am i missing something here?

Answer 1

It’s called autoboxing/unboxing.

As of Java 1.5, the compiler automatically “boxes” primitives into their corresponding class (eg int and Integer, double and Double etc), and un-boxes as required.

See this page in the documentation for more details.