Java Reference
In-Depth Information
import statement.
word import , followed by a member access operator-separated list of package and
subpackage names, followed by a type name or * (asterisk), followed by a semicolon.
The * symbolisawildcardthatrepresentsallunqualifiedtypenames.Ittellsthecom-
name is found in a previously searched package. (Using the wildcard does not have a
performance penalty or lead to code bloat, but can lead to name conflicts, as you will
Forexample, import; tells
the compiler that an unqualified Circle class exists in the package. Similarly, import*; tells the compiler tolookinthis pack-
age if it encounters a Rectangle class, a Triangle class, or even an Employee
class (if Employee has not already been found).
Tip Youshouldavoidusingthe * wildcardsothatotherdeveloperscaneasilysee
which types are used in source code.
statement must be expressed in the same case as that used in the package statement.
When import statements are present in source code, only a package statement and
comments can precede them.
Caution Placinganythingotherthanapackagestatement,importstatements,static
the compiler to report an error.
You can run into name conflicts when using the wildcard version of the import
statement because any unqualified type name matches the wildcard. For example, you
have graphics.shapes and geometry packages that each contain a Circle
class, the source code begins with import geometry.*; and import graph-
ics.shape.*; statements, and it also contains an unqualified occurrence of
Circle . Because the compiler does not know if Circle refers to geometry 's
Circle classor graphics.shape 's Circle class,itreportsanerror.Youcanfix
this problem by qualifying Circle with the correct package name.
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