1. IO in java

2. Stream
A stream is a sequence of data.In Java a stream is composed of bytes.
System.out
System.on
System.err
Character Stream
Byte Stream

3. Character & ByteStream classes

4. File class includes properties of a file or directory.
Ex: Create a file, read and write permission, last modified, length.
The File object represents the actual file/directory on the disk.

5. Constructor File(File parent, String child) File(String pathname)
File(String parent, String child)

6. Methods public String getName() public String getParent()
public String getPath()
public String getAbsolutePath()
public boolean canRead()
public boolean canWrite()
public boolean isDirectory()
public boolean isFile()

7. public long lastModified()
public long length()
public boolean delete()
public boolean createNewFile() throws IOException
public boolean exists()

8. PATH Separator for File in Java
In Microsoft Windows platform its “\” 
In Unix and Linux platform its forward slash “/”.
You can access file system separator in Java by system property file.separator and its also made available from File Class by public static field separator.

9. Character Stream FileReader FileWriter Object Reader Writer
Buffered Reader
InputStream Reader
FileReader
Writer
BufferedWriter
OutputStreamWriter
FileWriter
Print Writer
Character Stream

10. FileWriter Constructor (throws IOException)
FileWriter(String filepath)
FileWriter(String filepath, boolean append)
FileWriter(File obj)
Methods (of superclass Writer)
void close()
void write(char c[]), void write (int c)
void write(String s)

11. FileReader Constructor (may throw Exception)
FileReader(String filepath)
FileReader(File obj)
Methods (of superclass Reader)
void close()
int read()
int read(char c[])

12. Character Stream
FileWriter
FileReader

13. Buffered Character Stream
BufferedReader
BufferedWriter
By buffering, no. of reads and writes to the physical device is reduced.

14. BufferedWriter It buffers output to a character stream. Constructor:
BufferedWriter(Writer w)
BufferedWriter(Writer w, int bufsize)
Methods: same as Writer
void newLine() throwsIOException
program

15. BufferedReader It buffers input from character stream. Constructor:
BufferedReader(Reader r)
BufferedReader (Reader r, int bufsize)
Methods: same as Reader
void readLine() throwsIOException
program

16. PrintWriter
It displays string equivalents of simple type such as int, float, char, etc..
Constructor:
PrintWriter(OutputStream os)
PrintWriter(OutputStream os,boolean flushOnNewline)
PrintWriter(Writer w)
PrintWriter(Writer w, os,boolean flushOnNewline)

17. Methods:
print()
println()
program:

18. Why Use Files for I/O?
Keyboard input, screen output deal with temporary data
When program ends, data is gone
Data in a file remains after program ends
Can be used next time program runs
Can be used by another program

19. Text Files and Binary Files
All data in files stored as binary digits
Long series of zeros and ones
Files treated as sequence of characters called text files
Java program source code is one example
Can be viewed, edited with text editor
All other files are called binary files
Movie files, music files, Java class files
Access requires specialized program

20. ByteStream
Allows a programmer to work with binary data in a file.

21. Buffered Output Stream
Object
Input Stream
FileInput Stream
FilterInput Stream
Buffered Input Stream
Data Input Stream
Output Stream
FileOutputStream
FilterOutput Stream
Buffered Output Stream
Data Output Stream
PrintStream
Byte Stream

22. FileOutputStream It allows you to write binary data to a file.
If you have to write primitive values then use FileOutputStream
Constructor:
FileOutputStream(String filePath) throws IOException
FileOutputStream(File obj) throws IOException
Program

23. Methods (OutputStream class)
void close()
void write(byte c[])
All throws IOException

24. FileInputStream It allows you to read binary data from a file.
It should be used to read byte-oriented data for example to read image, audio, video
Constructor:
FileInputStream(String filePath) throws FileNotFoundException
FileInputStream(File obj) throws FileNotFoundException
Program

25. Methods(of InputStream class)
void close()
int read()
int read(byte b[])

26. InputStreamReader
behaves as bridge from bytes stream to character stream.
InputStreamReader (InputStream in)
InputStreamReader (InputStream in, String encoding)
void close ()
Int read ()

27. OutputStreamWriter
behaves as a bridge to transfer data from character stream to byte stream
OutputStreamWriter (OutputStream out)
OutputStreamWriter (OutputStream out, String encoding)
void close ()
void write (int c)
void write (char [] buffer, int offset, int length)

28. Character Encoding scheme for representing characters
JAVA - 16 bit Unicode character encoding
host platform may use different encoding scheme - the encoding of the platform may be specified.
UTF UniCode Transformation Format

29. DataOutputstream Class
It allows to write simple java types to byte output stream.
Constructor:
DataOutputStream(OutputStream os)

30. Methods void writeInt(int i) Void writeBoolean(Boolean b)
Void writeByte(Byte b)
Void writeChar(int i)
Void writeDouble(double d)
Void writeFloat(float f)
Void writeLong(long l)
Void writeShort(short s)
Void writeUTF(String s)
Program

31. DataInputStream
It allows to read simple java types from byte input stream.
Constructor:
DataInputStream(InputStream is)

32. Methods byte readByte() boolean readBoolean char readChar()
double readDouble()
float readFloat()
long readLong()
short readShort()
int readInt()
string readUTF()
Program

33. BufferedOutputStream
Buffers output to a byte stream.
Constructor:
BufferedOutputStream(OutputStream os)
BufferedOutputStream(OutputStream os, int bufSize)
Program:

34. BufferedInputStream Buffers input from a byte stream. Constructor:
BufferedInputStream(InputStream is)
BufferedInputStream(InputStream is, int bufSize)
Program:

35. Random Access File
Previous classes only use sequential access to read and write to a file.
This class allows to write programs that can seek to any location in a file to read & write data to that point.
Constructor:
RandomAccessFile(String filenm, String mode)

36. Methods void close() long length() int read()
int read(byte buffer[],int index, int size)
void seek(long n)
int skipByte(int n)