The document discusses various character stream classes in Java. CharacterArrayReader is used to read an array of characters from a memory buffer. CharArrayWriter is used for writing an array of characters to a memory buffer. BufferedReader improves performance by buffering input, while BufferedWriter ensures data buffers are physically written to the output stream. Examples are provided to demonstrate using these classes.

1. CharacterStream Classes
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2. Objectives
On completion of this period, you would be able
to learn
• CharacterStream classes
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3. Recap
In the last class, we have studied about
CharacterStream classes
• Where character stream classes deal with the
character oriented text
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4. CharArrayReader class
• Is an implementation of an input stream that
uses a character array as the source
• Is used to read an array of characters from a
memory buffers
• Constructors
• CharArrayReader(char array[ ])
• CharArrayReader(char array[ ], int start, int
numChars)
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5. Example:
// Demonstrate CharArrayReader.
import java.io.*;
public class CharArrayReaderDemo {
public static void main(String args[]) throws
IOException {
string tmp = "abcdefghijklmnopqrstuvwxyz";
int length = tmp.length();
char c[] = new char[length];
tmp.getChars(0, length, c, 0);
CharArrayReader input1 =new CharArrayReader(c);
CharArrayReader input2 = new CharArrayReader(c,
0, 5);
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6. Example: contd..
int i;
System.out.println("input1 is:");
while((i = input1.read()) != -1) {
System.out.print((char)i); }
System.out.println();
System.out.println("input2 is:");
while((i = input2.read()) != -1) {
System.out.print((char)i); }
System.out.println(); } }
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7. CharArrayWriter class
• CharArrayWriter is an implementation of an
output stream that uses an array as the
destination
• It is used for writing an array of characters to a
memory buffer
• CharArrayWriter has two constructors
• CharArrayWriter( )
• CharArrayWriter(int numChars)
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8. BufferedReader class
• BufferedReader improves performance by
buffering input
• This class is used to increase the efficiency of
reading
• It cannot directly access any source
• It has two constructors
• BufferedReader(Reader input Stream)
• BufferedReader(Reader input Stream, int bufSize)
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9. BufferedWriter class
• A Buffered Writer is a Writer that adds a
flush( ) method that can be used
• To ensure that data buffers are physically
written to the actual output stream
• Buffered Writer can increase performance by
reducing the number of times data is actually
physically written to the output stream
• Constructors
• BufferedWriter(Writer outputStream)
• BufferedWriter(Writer outputStream, int bufSize)
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10. Example:2
// Program for word count for a given input file
import java.io.*;
class WordCount {
public static int words = 0;
public static int lines = 0;
public static int chars = 0;
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11. Example:2 contd..
public static void wc (InputStreamReader isr)
throws IOException {
int c = 0;
boolean lastWhite = true;
String whiteSpace = " tnr";
while ((c = isr.read()) != -1) {
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12. Example:2 contd..
// count characters
chars++;
if (c == 'n') {
// Count lines
lines++; }
// Count words by detecting the start of a word
int index = whiteSpace.indexOf(c);
}
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13. Example:2 contd..
if(index == -1) {
if(lastWhite == true) {
++words; }
lastWhite = false; }
else {
lastWhite = true; } }
if(chars != 0) {
++lines; } }
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14. Example:2 contd..
public static void main(String args[]) {
FileReader fr;
try {
if (args.length == 0) { // We're working with stdin
wc(new InputStreamReader(System.in)); }
else { // We're working with a list of files
for (int i = 0; i < args.length; i++) {
fr = new FileReader(args[i]);
wc(fr); } } }
catch (IOException e) {
return; }
System.out.println(lines + " " + words + " " +
chars); } }
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15. Summary
• CharacterArrayReader an implementation of an
input stream that uses a character array as the
source and
• Used to read an array of characters from a
memory buffers
• CharArrayWriter is used for writing an array of
characters to a memory buffer
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16. Summary contd..
• BufferedReader improves performance by
buffering input
• BufferWriter ensures that data buffers are
physically written to the actual output stream
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17. Quiz
1. Which stream is used to read an array of
characters from a memory buffers
1. CharArrayReader
2. CharArrayWriter
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18. Quiz contd..
2. Which stream is used for writing an array of
characters to a memory buffer
1. CharArrayWriter
2. CharArrayReader
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19. Frequently Asked Questions
• Write about CharArrayReader, CharArrayWriter
• Write about BufferedReader, and BufferedWriter
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