Java I/O Part 1
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Java I/O Part 1

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File Handling in java

File Handling in java

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Java I/O Part 1 Presentation Transcript

  • 1. File IO in Java Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 September 18, 2012Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 1
  • 2. AGENDAUnderstanding StreamsStreamsFilesFile class methodsFile class methods -ContPrograms using File classProgram to rename a file.Program to delete a file.Types of StreamsStream Base IOOverview of IO ClassesOutputStream of IOInputStream of IOWriter of IOReader of IO Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 2
  • 3. Understanding Streams Input Stream Output Stream Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 3
  • 4. Streams Sequence of bytes. Input Stream : Data is received by some device to program. Output Stream : Data is sent by the program to device. Stream provides a sort of abstraction. Recall System.out and System.in System.in object of InputStream and System.out and System.err is object of PrintStream class. Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 4
  • 5. Streams Sequence of bytes. Input Stream : Data is received by some device to program. Output Stream : Data is sent by the program to device. Stream provides a sort of abstraction. Recall System.out and System.in System.in object of InputStream and System.out and System.err is object of PrintStream class. Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 5
  • 6. Streams Sequence of bytes. Input Stream : Data is received by some device to program. Output Stream : Data is sent by the program to device. Stream provides a sort of abstraction. Recall System.out and System.in System.in object of InputStream and System.out and System.err is object of PrintStream class. Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 6
  • 7. Streams Sequence of bytes. Input Stream : Data is received by some device to program. Output Stream : Data is sent by the program to device. Stream provides a sort of abstraction. Recall System.out and System.in System.in object of InputStream and System.out and System.err is object of PrintStream class. Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 7
  • 8. Streams Sequence of bytes. Input Stream : Data is received by some device to program. Output Stream : Data is sent by the program to device. Stream provides a sort of abstraction. Recall System.out and System.in System.in object of InputStream and System.out and System.err is object of PrintStream class. Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 8
  • 9. Streams Sequence of bytes. Input Stream : Data is received by some device to program. Output Stream : Data is sent by the program to device. Stream provides a sort of abstraction. Recall System.out and System.in System.in object of InputStream and System.out and System.err is object of PrintStream class. Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 9
  • 10. Files File class is provided by java.io package. An abstract reprsentation of file and directory pathnames. Note File object is not for reading / writing files. Used for obtaining information associated with file like permission, time and date, path. Directory too is treated as file and have additional method list() to list the filename in directory. public File(String pathname) public File(String parent, String child) public File(File parent, String child) public File(URI uri Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 10
  • 11. Files File class is provided by java.io package. An abstract reprsentation of file and directory pathnames. Note File object is not for reading / writing files. Used for obtaining information associated with file like permission, time and date, path. Directory too is treated as file and have additional method list() to list the filename in directory. public File(String pathname) public File(String parent, String child) public File(File parent, String child) public File(URI uri Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 11
  • 12. Files File class is provided by java.io package. An abstract reprsentation of file and directory pathnames. Note File object is not for reading / writing files. Used for obtaining information associated with file like permission, time and date, path. Directory too is treated as file and have additional method list() to list the filename in directory. public File(String pathname) public File(String parent, String child) public File(File parent, String child) public File(URI uri Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 12
  • 13. Files File class is provided by java.io package. An abstract reprsentation of file and directory pathnames. Note File object is not for reading / writing files. Used for obtaining information associated with file like permission, time and date, path. Directory too is treated as file and have additional method list() to list the filename in directory. public File(String pathname) public File(String parent, String child) public File(File parent, String child) public File(URI uri Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 13
  • 14. Files File class is provided by java.io package. An abstract reprsentation of file and directory pathnames. Note File object is not for reading / writing files. Used for obtaining information associated with file like permission, time and date, path. Directory too is treated as file and have additional method list() to list the filename in directory. public File(String pathname) public File(String parent, String child) public File(File parent, String child) public File(URI uri Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 14
  • 15. Files File class is provided by java.io package. An abstract reprsentation of file and directory pathnames. Note File object is not for reading / writing files. Used for obtaining information associated with file like permission, time and date, path. Directory too is treated as file and have additional method list() to list the filename in directory. public File(String pathname) public File(String parent, String child) public File(File parent, String child) public File(URI uri Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 15
  • 16. File class methods boolean canRead() boolean canWrite() boolean cancreateNewFile() boolean delete() boolean exists() String getAbsolutePath() String getName() String getParent() String getPath() boolean isAbsolute() boolean isDirectory() boolean isFile() boolean isHidden() long lastModified() long length() Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 16
  • 17. File class methods -Cont String[] list() File[] listFiles() boolean mkdir() boolean renameTo(File d) boolean setLastModifiedDate() boolean setReadOnly() String toString() String getFreeSpace() String getTotalSpace() String getUsableSpace() Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 17
  • 18. Programs using File class Program to rename a file. Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 18
  • 19. Programs using File class Program to rename a file. Program to delete a file. Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 19
  • 20. Programs using File class Program to rename a file. Program to delete a file. Creating a directory. Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 20
  • 21. Programs using File class Program to rename a file. Program to delete a file. Creating a directory. Traversing a Directory. Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 21
  • 22. Programs using File class Program to rename a file. Program to delete a file. Creating a directory. Traversing a Directory. Using FilenameFilter Interface. Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 22
  • 23. Program to rename a file. import java.io.*; import java.util.Scanner; public class Rename { public static void main(String args[]) { File f1, f2; Scanner s = new Scanner(System.in); System.out.println("Enter the file name : "); String name old = s.nextLine(); System.out.println("Enter the new name : "); String name new = s.nextLine(); f1 = new File(name old); f2 = new File(name new); if(f1.renameTo(f2)) System.out.println("File renamed"); else System.out.println("Error Occured"); Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 23
  • 24. Program to delete a file. import java.io.*; import java.util.Scanner; public class Rename { public static void main(String args[]) { File f1; Scanner s = new Scanner(System.in); System.out.println("Enter the file name : "); String name = s.nextLine(); f1 = new File(name); if(f1.exists()) { if(f1.delete()) System.out.println("File deleted"); else System.out.println("Error Occured"); } Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 24
  • 25. Types of Streams Byte Stream / Binary Stream Only Binary data / bytes. Read and Write [8 bytes]. Character Stream Character Data. Unicode Character. Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 25
  • 26. Types of Streams Byte Stream / Binary Stream Only Binary data / bytes. Read and Write [8 bytes]. Character Stream Character Data. Unicode Character. Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 26
  • 27. Stream Base IO Four Abstract Classes. Byte Stream / Binary Stream InputStream. OutputStream. Character Stream Reader. Writer. Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 27
  • 28. Stream Base IO Four Abstract Classes. Byte Stream / Binary Stream InputStream. OutputStream. Character Stream Reader. Writer. Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 28
  • 29. Overview of IO Classes Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 29
  • 30. OutputStream of IO Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 30
  • 31. InputStream of IO Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 31
  • 32. Writer of IO Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 32
  • 33. Reader of IO Prof. AshishSingh Bhatia, ast.bhatia@gmail.com, ashish@asbspace.in, Web: asbspace.in, M:9879009551 33