Name Ambiguities

[Enkita mody]

Name Ambiguities

If a member in one package shares its name with a member in another package and both packages are imported, you must refer to each member by its qualified name. For example, the graphics package defined a class named Rectangle. The java.awt package also contains a Rectangle class. If both graphics and java.awt have been imported, the following is ambiguous.

Rectangle rect;

In such a situation, you have to use the member's fully qualified name to indicate exactly which Rectangle class you want. For example,

graphics.Rectangle rect;

If there is a such circumstance then it doesn't make any sense to import them when ultimately we have to use fully qualified name.

[Matthew Brown]

ankita modi. wrote:If there is a such circumstance then it doesn't make any sense to import them when ultimately we have to use fully qualified name.

In those circumstances, no, there's, no need to import them. It's relatively rare, though.

[Bear Bibeault]

For me it's java.util.Date and java.sql.Date. Though that pretty much gets resolved by using JPA.

[Rob Spoor]

In the old days, java.awt.List and java.util.List also could cause conflicts. They still can if you import java.awt.* and java.util.*.
java.io.FileFilter and javax.swing.filechooser.FileFilter also can cause conflicts, especially since both share approximately the same purpose. I'm still annoyed that javax.swing.filechooser.FileFilter does not implement java.io.FileFilter because it already has its sole method.

[Ivan Jozsef Balazs]

Rob Spoor wrote:I'm still annoyed that javax.swing.filechooser.FileFilter does not implement java.io.FileFilter because it already has its sole method.

This reduces the dependency across different packages.
But you can derive a class from it having only the constructors and the "implements" clause.

[Enkita mody]

import static java.lang.Integer.MAX_VALUE;
import static java.lang.Long.MAX_VALUE;
class Ambiguity 
{
	public static void main(String[] args) 
	{
                //System.out.println("MAX_VALUE = "+MAX_VALUE);
	}
}

I didn't ever try to access MAX_VALUE in program then Why there is compile error ?

[Matthew Brown]

With those import statements, you're telling the compiler "I want to be able to refer to both Integer.MAX_VALUE and Long.MAX_VALUE as simply MAX_VALUE. The compiler's smart enough to realise that doesn't make sense, even without you trying to use them.