Why some Java codes imports same package again? [duplicate]

Question

Possible Duplicate:
Java import confusion

When i read play frameworks documentation, I found this.

import play.*;
import play.mvc.*; 

In the first line itself they have imported all the classes under play package. Then what is the use of second line. Check this link. Go to 'Providing an application error page' section.

Correct me if i'm wrong in imports concept.

Answer 1

Correct me if i'm wrong in imports concept.

You are.

Something like this:

import foo.bar.*;

only imports types from the foo.bar package. It doesn't import from "subpackages" such as foo.bar.baz.

It's very easy to test this:

import java.util.*;

class Test {
    public void foo() {
        Pattern p = null;
    }
}

That won't compile, but if you add:

import java.util.regex.*;

then it will.

Java doesn't really think of packages as forming a hierarchy. We do, as humans, but as far as the Java language is concerned, the packages java.util and java.util.regex are entirely unrelated.

Answer 2

import play.*;

will import all the types within; except those which are inside a sub-package.

import play.mvc.*; 

will import all the types within mvc package, which is sub-pckage within play.

You'll find this answer also helpful: Java import confusion

Answer 3

The first line will import all classes, enums and interfaces in the same level of play.* but no subpackages. Therefore you need the second line.