Byte stream classes.49

Byte stream classes.49

• 1.
  ByteStream classes http://improvejava.blogspot.in/ 1
• 2.
  Objective On completion ofthis period, you would be able to learn • ByteStream classes http://improvejava.blogspot.in/ 2
• 3.
  Recap In the lastclass, you have studied about the File class • You have also studied about the various methods, and properties of a File class http://improvejava.blogspot.in/ 3
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  Types of StreamClass Java’s stream-based I/O is built upon four abstract classes: 1. Input Stream 2. Output Stream 3. Reader 4. Writer http://improvejava.blogspot.in/ 4
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  Byte Streams Byte Streamsare two types 1. InputStream class 2. OutputStream class http://improvejava.blogspot.in/ 5
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  InputStream class • Datais accessed as a sequence of bytes • Its an abstract class that defines streaming byte input • The methods in the input stream are used to read bytes from input stream • All methods in this class will throw an I/O Exception http://improvejava.blogspot.in/ 6
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  OutputStream class • Isan abstract class that defines streaming byte output • The methods of it are used to send bytes to the output stream • All methods in this class return a void value and throw an I/O Exception in the case of errors http://improvejava.blogspot.in/ 7
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  FileInputStream class • Isa subclass of InputStream that you can use to read bytes from a file • Its has two constructors • FileInputStream(String filePath) • FileInputStream(File fileObj) • When FileInputStream is created, it is also opened for reading • FileInputStream overrides six of the methods in the abstract class InputStream http://improvejava.blogspot.in/ 8
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  // Program forFileInputStream import java.io.*; class FileInputStreamDemo { public static void main(String args[]) throws Exception { int size; InputStream f = new FileInputStream("FileInputStreamDemo.java"); System.out.println("Total Available Bytes: " + (size = f.available())); int n = size/40; System.out.println("First " + n + " bytes of the file one read() at a time"); for (int i=0; i < n; i++) { System.out.print((char) f.read()); } System.out.println("nStill Available: " + f.available()); System.out.println("Reading the next " + n + " with one read(b[])"); http://improvejava.blogspot.in/ 9
• 10.
  // Program forFileInputStream byte b[] = new byte[n]; if (f.read(b) != n) { System.err.println("couldn't read " + n + " bytes."); } System.out.println(new String(b, 0, n)); System.out.println("nStill Available: " + (size = f.available())); System.out.println("Skipping half of remaining bytes with skip()"); f.skip(size/2); System.out.println("Still Available: " + f.available()); System.out.println("Reading " + n/2 + " into the end of array"); if (f.read(b, n/2, n/2) != n/2) { System.err.println("couldn't read " + n/2 + " bytes."); } System.out.println(new String(b, 0, b.length)); System.out.println("nStill Available: " + f.available()); f.close(); } } http://improvejava.blogspot.in/ 10
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  FileOutputStream class • Isa subclass of OutputStream that you can use to write bytes to a file • Constructors are • FileOutputStream(String filePath) • FileOutputStream(File fileObj) • FileOutputStream(String filePath, boolean append) • FileOutputStream(File fileObj, boolean append) • They can throw a FileNotFoundException or a SecurityException http://improvejava.blogspot.in/ 11
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  Summary • Byte Streams are two types: InputStream and OutputStream • In InputStream data is accessed as a sequence of bytes • FileInputStream and FilOuputStream are the subclasses of ByteStream http://improvejava.blogspot.in/ 12
• 13.
  Quiz 1. All methodsin InputStream class will throw an IOException A. True B. False http://improvejava.blogspot.in/ 13
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  Quiz contd .. 2. Which method is used to read bytes from InpuStream A. readLine() B. read() C. write() D. None http://improvejava.blogspot.in/ 14
• 15.
  Frequently Asked Questions 1.Write about Byte Stream classes 2. Write a java program which illustrates the use of FileInputStream http://improvejava.blogspot.in/ 15