Java IO.pdf - Nguyen Dang Binh

Java I/O
The isHidden() method, only available in Java 2 and later, returns true if the file exists but
is hidden; that is, it does not appear in normal displays or listings. It returns false if the file
isn't hidden or doesn't exist.
public boolean isHidden() // Java 2
Exactly how a file is hidden varies from platform to platform. On Unix, any file whose name
begins with a period is hidden. On Windows and the Mac, hidden files are identified by
particular attributes. This method throws a security exception if the security manager doesn't
allow the file to be read.
The lastModified() method returns a long indicating the last time this file was modified:
public long lastModified()
Java 2 specifies that the long returned is the number of milliseconds since midnight, January
1, 1970, Greenwich Mean Time. However, in earlier VMs the conversion between this long
and a real date is platform-dependent, so it's only useful for comparing the modification dates
of different files, not for determining the absolute time a file was modified. This method
throws a security exception if the security manager doesn't allow the file to be read. It returns
if the file doesn't exist or the last modified date can't be determined.
Finally, the length() method returns the number of bytes in the file or if the file does not
exist:
public long length()
This method throws a security exception if the security manager doesn't allow the file to be
read.
12.3.3.7 An example
Example 12.4 is a character-mode program that lists all the available information about files
named on the command line. Names may be given as absolute or relative paths.
Example 12.4. The FileSpy Program
import java.io.*;
import java.util.*;
public class FileSpy {
public static void main(String[] args) {
for (int i = 0; i < args.length; i++) {
File f = new File(args[i]);
if (f.exists()) {
System.out.println("Name: " + f.getName());
System.out.println("Absolute path: " + f.getAbsolutePath());
try {
System.out.println("Canonical path: " + f.getCanonicalPath());
}
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