BINARY I/O - Introduction to Java Programming - page 733

C HAPTER S UMMARY

1.

I/O can be classified into text I/O and binary I/O . Text I/O interprets data in
sequences of characters. Binary I/O interprets data as raw binary values. How text is
stored in a file depends on the encoding scheme for the file. Java automatically per-
forms encoding and decoding for text I/O.

2.

The InputStream and OutputStream classes are the roots of all binary I/O
classes. FileInputStream/FileOutputStream associates a file for input/output.
BufferedInputStream / BufferedOutputStream can be used to wrap any binary
I/O stream to improve performance. DataInputStream / DataOutputStream can
be used to read/write primitive values and strings.

3. ObjectInputStream / ObjectOutputStream can be used to read/write objects
in addition to primitive values and strings. To enable object serialization , the
object's defining class must implement the java.io.Serializable marker
interface.

4.

The RandomAccessFile class enables you to read and write data to a file. You can
open a file with the r mode to indicate that it is read-only, or with the rw mode to
indicate that it is updateable. Since the RandomAccessFile class implements
DataInput and DataOutput interfaces, many methods in RandomAccessFile are
the same as those in DataInputStream and DataOutputStream .

T EST Q UESTIONS

Do the test questions for this chapter online at www.cs.armstrong.edu/liang/intro9e/test.html .

P ROGRAMMING E XERCISES

Section 19.3
*19.1

( Create a text file ) Write a program to create a file named Exercise19_01.txt if it
does not exist. Append new data to it if it already exists. Write 100 integers created
randomly into the file using text I/O. Integers are separated by a space.

Section 19.4
*19.2

( Create a binary data file ) Write a program to create a file named
Exercise19_02.dat if it does not exist. Append new data to it if it already exists.
Write 100 integers created randomly into the file using binary I/O.

*19.3

( Sum all the integers in a binary data file ) Suppose a binary data file
named Exercise19_03.dat has been created and its data are created using
writeInt(int) in DataOutputStream . The file contains an unspecified num-
ber of integers. Write a program to find the sum of the integers.

*19.4

( Convert a text file into UTF ) Write a program that reads lines of characters from
a text file and writes each line as a UTF-8 string into a binary file. Display
the sizes of the text file and the binary file. Use the following command to run
the program:

java Exercise19_04 Welcome.java Welcome.utf