Java I/O Part 2

File IO in Java

Prof. AshishSingh Bhatia, [email protected],[email protected], Web: asbspace.in, M:9879009551

September 21, 2012

Prof. AshishSingh Bhatia, [email protected], [email protected], Web: asbspace.in, M:9879009551 1

AGENDA

Overview of IO Classes

OutputStream of IO

InputStream of IO

Writer of IO

Reader of IO

Methods of OutputStream Class

Methods of Writer Class

Methods of Writer Class Extra

Methods of InputStream Class

Methods of Reader Class

InputStream Usage

OutputStream Usage

Bridge Classes

OutputStreamWriter

InputStream Reader

FileInput and FileOutput StreamProf. AshishSingh Bhatia, [email protected], [email protected], Web: asbspace.in, M:9879009551 2

Overview of IO Classes


OutputStream of IO


InputStream of IO


Writer of IO


Reader of IO



I public void write(int b)

Writes a single byte to an output stream. Why we need int asargument?

I public void write(byte[] b)

Writes complete byte array in to an outputstream.

I public void write(byte[] b, int offset, int len)

Write a subrange from offset to specified length[number ofbytes].

I public void flush()

Flushes the output buffer. Ensures the contents are written tothe destination.

I public void close()

Closes the outputstream. Further write will generateIOException



I public void write(int ch)

Writes a single character to an output stream. Why we needint as argument?

I public void write(char[] ch)

Writes complete character array in to an outputstream.

I public void write(char[] b, int offset, int len)

Write a subrange from offset to specified length[number ofcharacter].




Closes the writer. Further write will generate IOException



I String is a sequence of Character.

I public void write(String s)

I public void write(String s, int offset, int len)

I public void append(char ch)

I public void append(CharSequence cs)

I public void append(CharSequence cs, int offset,

int len)









int len)



I public int read()

Read the integer representation of the next available byte ofinput. Returns -1 when the end of file is encountered.

I public int read(byte[] b)

Attempt to read up to b.length bytes in the the b array.Returns the number of actual bytes read. -1 is returned whenthe end of file is encountered.

I public int read(byte[] b, int offset, int len)I public long skip(long count)

count indicates number of bytes to be skipped and return thenumber of byte skipped or -1 in case of end of file.

I public int available()

Number of bytes available for reading.I public void mark(int readlimit)I public void reset()I public boolean markSupported()I public void close()



I public int read()










I public int read()




I public int read(byte[] b, int offset, int len)

I public long skip(long count)






I public int read()










I public int read()







Number of bytes available for reading.

I public void mark(int readlimit)I public void reset()I public boolean markSupported()I public void close()



I public int read()







Number of bytes available for reading.I public void mark(int readlimit)

I public void reset()I public boolean markSupported()I public void close()



I public int read()







Number of bytes available for reading.I public void mark(int readlimit)I public void reset()

I public boolean markSupported()I public void close()



I public int read()







Number of bytes available for reading.I public void mark(int readlimit)I public void reset()I public boolean markSupported()




I public int read()







Number of bytes available for reading.I public void mark(int readlimit)I public void reset()I public boolean markSupported()I public void close()Prof. AshishSingh Bhatia, [email protected], [email protected], Web: asbspace.in, M:9879009551 31


I public int read()

I public int read(char[] b)

I public int read(char[] b, int offset, int len)


I public boolean ready()

I public void mark(int readlimit)

I public void reset()

I public boolean markSupported()




I public int read()










InputStream Usage


OutputStream Usage


Bridge Classes

I OutputStreamWriter and InputStreamReader

I Character Base Stream Classes which inturns work on bytes.

I Handles unicode character and bytes both.

I Encoding and Decoding of unicode character from and tovarious character set.

I java.nio.charset package has classes which handleencoding and decoding.

I class Charset represents different character set.


OutputStreamWriter


InputStream Reader


FileInput and FileOutput Stream

I Output and input of binary files.

I FileOutputStream create and write bytes in to physical file.

I If file exists it overwrites it until append flag is used.

I Inherits all the methods from the OutputStream.

I Additional methods arepublic FileDescriptor getFD()

public FileChannel getChannel()


FileDescriptor

I Whenever any file is opened for input or output, it uses a filedescriptor.

I 0=Standard Input

I 1=Standard Output

I 2=Standard Error


FileDescriptor


I 0=Standard Input

I 1=Standard Output

I 2=Standard Error


Java I/O Part 2

Education

Transcript of Java I/O Part 2