Java Reference
In-Depth Information
The conversion of a pathname string to or from an abstract pathname is inherently
names within it are separated by the default name-separator character or by any other
name-separator character that is supported by the underlying platform. For example,
File(String pathname) converts pathname string /x/y to abstract pathname
/x/y onaUnixorLinuxplatform,andthissamepathnamestringtoabstractpathname
\x\y on a Windows platform.
Note The default name-separator character is obtainable from system property
file.separator , and is also stored in File 's separator and separator-
Char class fields. The first field stores the character in a java.lang.String in-
stance and the second field stores it as a char value. Neither name of these final
fields follows the convention of appearing entirely in uppercase.
ated from the next by a single copy of the default name-separator character.
File offersadditionalconstructorsforinstantiatingthisclass.Forexample,thefol-
lowing constructors merge parent and child pathnames into combined pathnames that
are stored in File objects:
File(String parent, String child) createsanew File instance
from a parent pathname string and a child pathname string.
File(File parent, String child) creates a new File instance
from a parent pathname File instance and a child pathname string.
Eachconstructor's parent parameterispasseda parent pathname ,astringthatcon-
sistsofallpathnamecomponentsexceptforthelastname,whichisspecifiedby child .
The following statement demonstrates this concept via File(String, String) :
File file3 = new File("prj/books/", "bj7");
Theconstructormergesrelativeparentpathname prj/books/ withchildpathname
bj7 into relative pathname prj/books/bj7 . (If I had specified prj/books as
the parent pathname, the constructor would have added the separator character after
books .)
Tip Because File(String pathname) , File(String parent,
String child) , and File(File parent, String child) don't detect
invalid pathname arguments (apart from throwing
java.lang.NullPointerException when pathname or child is null ),
you must be careful when specifying pathnames. You should strive to only specify
Search WWH ::

Custom Search