1. FILE OBJECTS & TYPES OF FILE –
TEXT VS BINARY
Chapter 10.1:

2. File
 File is regarded as a collection of bytes
 When a file is read, computer delivers some of
those bytes to the program.
 When a file is written, computer accepts some
bytes from the program and saves them in part of
the file.
 Computer makes no distinction between eg. image
files and text files. Its all bytes to the hardware.
What those bytes are used for is up to the
software.

3. Types of File
 All information in any file is kept in binary form.

4. Types of File
 File can be categorized as text (ASCII) file or binary
file.
 A text file is a file that contains bytes that represent:
 characters 'A' through 'Z'
 characters 'a' through 'z'
 characters '0' through '9'
 the space character
 punctuation and symbols like . , : ; " + - $ (and others)
 a few control characters that represent end of lines, tabs and
some other things.
using ASCII Codes
 A binary file is a file that contains bytes that represent
others (eg. numbers, image, audio, formatted text etc)

5. The File Class
 The File class (from java.io). can be used to obtain
info about file
 To do this, we must first create a File object
 A File object can represent a file or a directory
File inFile = new File(“sample.dat”);
File inFile = new File
(“C:/SamplePrograms/test.dat”);
Creates File object for
the file sample.dat in the
current directory.
Creates File object for
the file test.dat in the
directory
C:SamplePrograms
using the generic file
separator / and providing
the full pathname.

6. Some File Methods
if ( inFile.exists( ) ) {
if ( inFile.isFile() ) {
File directory = new
File("C:/JavaPrograms/Ch12");
String filename[] = directory.list();
for (int i = 0; i < filename.length; i++) {
System.out.println(filename[i]);
}
To see if inFile is
associated to a real file
correctly.
To see if inFile is
associated to a file. If
false, it is a directory.
Also, can test directly if it
is a directory.
List the name of all files
in the directory
C:JavaProjectsCh12
if ( inFile.isDirectory() ) {

7. Some File Methods
if ( inFile.length( ) ) {
if ( inFile.canRead() ) {
To see the size of the file
in bytes represented by
inFile
To see if inFile is
associated to a file that
exist & can be read
if ( inFile.canWrite() ) { To see if inFile is
associated to a file that
exist & can be written
if ( inFile.getName() ) { To get the name of the file
represented by inFile