7.5.2 Type-Import-on-Demand Declaration

A type-import-on-demand declaration allows all public types declared in the package named by a fully qualified name to be imported as needed.

TypeImportOnDemandDeclaration:

	import PackageName . * ;

It is a compile-time error for a type-import-on-demand declaration to name a package that is not accessible (§6.6), as determined by the host system (§7.2). Two or more type-import-on-demand declarations in the same compilation unit may name the same package; the effect is as if there were exactly one such declaration. It is not a compile-time error to name the current package or java.lang in a type-import-on-demand declaration, even though they are already imported; the duplicate type-import-on-demand declaration is ignored.

The example:

import java.util.*;

causes the simple names of all public types declared in the package java.util to be available within the class and interface declarations of the compilation unit. Thus, the simple name Vector refers to the type Vector in the package java.util in all places where it is not hidden (§6.3) by a single-type-import declaration of a type whose simple name is Vector; by a type named Vector and declared in the package to which the compilation unit belongs; or by a declaration of a field, parameter, or local variable named Vector. (It would be unusual for any of these conditions to occur.)