Why is import of class not needed when calling method on instance (Java)

Question

Something that\'s confused me - an example:

Thing.java:

import java.util.Date; 

class Thing { 
    static Date getDate() {return new Date();}
}
         


        

Answer 1

Good question !!

I think the result is the difference between how java compiler handles expressions vs statements.

Date d = new Date(); // a statement

where as

new Thing().getDate().getTime()

is an expression as it occurs inside println method call. When you call getDate on new Thing() the compiler tries to handle the expression by looking at the type info for Thing class, which is where it gets the declaration of type Date. But when you try to use Date separately in a statement like

Date d = new Thing().getDate();

you are assigning the result to a type in the current scope (class TestUsesThing ), compiler tries to resolve the type within that scope. As a result, you see the compiler error for unknown type.