- Java.io.RandomAccessFile Class provides a way to random access files using reading and writing operations. It works like an array of byte storted in the File.
- Declaration :
public class RandomAccessFile
extends Object
implements DataOutput, DataInput, Closeable
Methods of RandomAccessFile Class
- read() : java.io.RandomAccessFile.read() reads byte of data from file. The byte is returned as an integer in the range 0-255
public int read()
Parameters :
--------
Return :
reads byte of data from file, -1 if
end of file is reached.
- read(byte[] b) java.io.RandomAccessFile.read(byte[] b) reads bytes upto b.length from the buffer.
public int read(byte[] b)
Parameters :
b : buffer to be read
Return :
byte of data from file upto b.length,
-1 if end of file is reached.
- read((byte[] b, int offset, int len) : java.io.RandomAccessFile.read((byte[] b, int offset, int len) reads bytes initialising from offset position upto b.length from the buffer.
public int read(byte[] b, int offset, int len)
Parameters :
b : buffer to read
offset : starting position to read
len : max no of bytes to read
Return :
reads bytes initialising from offset position
upto b.length from the buffer.
- readBoolean() : java.io.RandomAccessFile.readBoolean() reads a boolean from the file.
public final boolean readBoolean()
Parameters :
------
Return :
boolean value
- readByte() : java.io.RandomAccessFile.readByte() reads a signed eight-bit value from file, start reading from the File Pointer.
public final byte readByte()
Parameters :
-------
Return :
signed eight-bit value from file
- readDouble() : java.io.RandomAccessFile.readDouble() reads a double value from the file, start reading from the File Pointer.
public final double readDouble()
Parameters :
------
Return :
reads a double value from the file.
- readFloat() : java.io.RandomAccessFile.readFloat() reads a float value from the file, start reading from the File Pointer.
public final double readFloat()
Parameters :
------
Return :
reads a float value from the file.
- readFully(byte[] b) : java.io.RandomAccessFile.readFully(byte[] b) reads bytes upto b.length from the buffer, start reading from the File Pointer.
public final void readFully(byte[] b)
Parameters :
b : buffer to be read
Return :
reads bytes initialising from offset position
upto b.length from the buffer
- readLong() : java.io.RandomAccessFile.readLong() reads a signed 64 bit integer from the file, start reading from the File Pointer.
public final long readLong()
Parameters :
-------
Return :
signed 64 bit integer from the file
// Java Program illustrating use of io
.RandomAccessFile class methods
// read(), read(byte[] b), readBoolean(),
readByte(), readInt()
// readFully(byte[] b,
int off, int len), readFully(), readFloat()
// readChar(), readDouble(),
import java.io.*;
public class NewClass
{
public static void mai(String[] args)
{
try
{
double d = 1.5;
float f = 14.56f;
// Creating a new RandomAccessFile
-"javaprogramer"RandomAccessFile
geek = new
("javaprogramer.txt", "rw");
// Writing to file
geek.writeUTF("Hello javaprogramer For
javaprogramer");
// File Pointer at index position - 0
javaprogramer.seek(0);
// read() method :
System.out.println("Use of read() method :
" + javaprogramerk.read());
javaprogramer.seek(0);
byte[] b = {1, 2, 3};
// Use of .read(byte[] b) method :
System.out.println("Use of
.read(byte[] b) : " + javaprogramer.read(b));
// readBoolean() method :
System.out.println("Use of readBoolean()
:" + geek.readBoolean());
// readByte() method :
System.out.println("Use of readByte() : "
+ geek.readByte());
javaprogramer.writeChar('c');
javaprogramer.seek(0);
// readChar() :
System.out.println("Use of readChar()
: "+ geek.readChar());
geek.seek(0);
geek.writeDouble(d);
geek.seek(0);
// read double
System.out.println("Use of readDouble()
: " + geek.readDouble());
geek.seek(0);
geek.writeFloat(f);
geek.seek(0);
// readFloat() :
System.out.println("Use of readFloat()
: "+ geek.readFloat());
geek.seek(0);
// Create array upto geek.length
byte[] arr = new byte[(int) geek.length()];
// readFully() :
geek.readFully(arr);
String str1 = new String(arr);
System.out.println
("Use of readFully() : " + str1);
geek.seek(0);
// readFully(byte[] b, int off, int len) :
geek.readFully(arr, 0, 8);
String str2 = new String(arr);
System.out.println("Use of readFully
(byte[] b, int off,
int len) : " + str2);
}
catch (IOException ex)
{
System.out.println
("Something went Wrong");
ex.printStackTrace();
}
}
}
Output :
Use of read() method : 0
Use of .read(byte[] b) : 3
Use of readBoolean() : true
Use of readByte() : 108
Use of readChar() : c
Use of readDouble() : 1.5
Use of readFloat() : 14.56
Use of readFully() :javaprogramer
For javaprogramer
Use of readFully(byte[] b, int off, int len) :
javaprogramer For javaprogramer
