Java IO.pdf - Nguyen Dang Binh

Java I/O
findResource() methods of java.lang.Class or java.lang.ClassLoader. This works
irrespective of the current working directory as long as the JAR archive has been placed
somewhere in the class path.
12.3 The File Class
When you consider all the difficulties of writing file access code that
works on all the platforms Java supports, you can become grateful that
applets aren't allowed to write files. Although this limits the sort of
applets you can write, perhaps what's really needed is not unlimited (or
even limited) file access but some non-file-oriented persistent storage
mechanism, probably some sort of database, that hides the
idiosyncrasies of each individual platform. JavaSoft is now working on
exactly such a mechanism called JavaSpaces, though it probably won't
appear in web browsers for some time
Instances of the java.io.File class represent filenames on the local system, not actual files.
Occasionally, this distinction is crucial. For instance, File objects can represent directories as
well as files. Also, you cannot assume that a file exists just because you have a File object
for a file.
public class File extends Object implements Serializable
In Java 2, the File class also implements the java.lang.Comparable interface:
public class File extends Object implements Serializable, Comparable //
Java 2
Although there are no guarantees that a file named by a File object actually exists, the File
class does contain many methods for getting information about the attributes of a file and for
manipulating those files. The File class attempts to account for system-dependent features
like the file separator character and file attributes, though in practice it doesn't do a very good
job, especially in Java 1.0 and 1.1.
Each File object contains a single String field called path that contains either a relative or
absolute path to the file, including the name of the file or directory itself:
private String path
Many methods in this class work solely by looking at this string. They do not necessarily look
at any part of the filesystem.
12.3.1 Constructing File Objects
The java.io.File class has three constructors. Each accepts some variation of a filename as
an argument. This one is the simplest:
public File(String path)
280