Packages  This Package  Prev  Next  Index  

public  class  java.io.RandomAccessFile
    extends  java.lang.Object  (I-§1.12)
    implements java.io.DataOutput  (I-§2.25),
               java.io.DataInput  (I-§2.24)
{
        // Constructors
    public RandomAccessFile(File  file, String  mode);	§2.20.1
    public RandomAccessFile(String  name, String  mode);	§2.20.2

        // Methods
    public void close();	§2.20.3
    public final FileDescriptor getFD();	§2.20.4
    public long getFilePointer();	§2.20.5
    public long length();	§2.20.6
    public int read();	§2.20.7
    public int read(byte  b[]);	§2.20.8
    public int read(byte  b[], int  off, int  len);	§2.20.9
    public final boolean readBoolean();	§2.20.10
    public final byte readByte();	§2.20.11
    public final char readChar();	§2.20.12
    public final double readDouble();	§2.20.13
    public final float readFloat();	§2.20.14
    public final void readFully(byte  b[]);	§2.20.15
    public final void readFully(byte  b[], int  off, int  len);	§2.20.16
    public final int readInt();	§2.20.17
    public final String readLine();	§2.20.18
    public final long readLong();	§2.20.19
    public final short readShort();	§2.20.20
    public final int readUnsignedByte();	§2.20.21
    public final int readUnsignedShort();	§2.20.22
    public final String readUTF();	§2.20.23
    public void seek(long  pos);	§2.20.24
    public int skipBytes(int  n);	§2.20.25
    public void write(byte  b[]);	§2.20.26
    public void write(byte  b[], int  off, int  len);	§2.20.27
    public void write(int  b);	§2.20.28
    public final void writeBoolean(boolean  v);	§2.20.29
    public final void writeByte(int  v);	§2.20.30
    public final void writeBytes(String  s);	§2.20.31
    public final void writeChar(int  v);	§2.20.32
    public final void writeChars(String  s);	§2.20.33
    public final void writeDouble(double  v);	§2.20.34
    public final void writeFloat(float  v);	§2.20.35
    public final void writeInt(int  v);	§2.20.36
    public final void writeLong(long  v);	§2.20.37
    public final void writeShort(int  v);	§2.20.38
    public final void writeUTF(String  str);	§2.20.39
}

Creates a random access file stream to read from, and optionally to write to, the file specified by the File argument.

The mode argument must either be equal to "r" or to "rw", indicating either to open the file for input, or for both input and output, respectively.

Parameters:

file - the file object

mode - the access mode

Throws

IOException (I-§2.29)

If an I/O error occurs.

Throws

IllegalArgumentException (I-§1.32)

If the mode argument is not equal to "r" or to "rw".

Throws

SecurityException (I-§1.43)

If a security manager exists, its checkRead method (I-§1.15.19) is called with the path name (I-§2.7.16) of the File argument to see if the application is allowed read access to the file. If the mode argument is equal to "rw", its checkWrite method (I-§1.15.19) also is called with the path name to see if the application is allowed write access to the file.

Creates an random access file stream to read from, and optionally to write to, a file with the specified name.

The mode argument must either be equal to "r" or "rw", indicating either to open the file for input or for both input and output.

Parameters:

name - the system dependent file name

mode - the access mode

Throws

IOException (I-§2.29)

If an I/O error occurs.

Throws

IllegalArgumentException (I-§1.32)

If the mode argument is not equal to "r" or to "rw".

Throws

SecurityException (I-§1.43)

If a security manager exists, its checkRead method (I-§1.15.19) is called with the name argument to see if the application is allowed read access to the file. If the mode argument is equal to "rw", its checkWrite method (I-§1.15.19) also is called with the name argument to see if the application is allowed write access to the file. Either of these may result in a security security exception (I-§1.43).

Closes this random access file stream and releases any system resources associated with the stream.

Throws

IOException (I-§2.29)

If an I/O error occurs.

Returns:

the file descriptor object (I-§2.8) associated with this stream.

Throws

IOException (I-§2.29)

If an I/O error occurs.

Returns the current offset in this file.

Returns:

the offset from the beginning of the file, in bytes, at which the next read or write occurs.

Throws

IOException (I-§2.29)

If an I/O error occurs.

Returns:

the length of this file.

Throws

IOException (I-§2.29)

If an I/O error occurs.

Reads a byte of data from this file. This method blocks if no input is yet available.

Returns:

the next byte of data, or -1 if the end of the file is reached.

Throws

IOException (I-§2.29)

If an I/O error occurs.

Reads up to b.length bytes of data from this file into an array of bytes. This method blocks until at least one byte of input is available.

Parameters:

b - the buffer into which the data is read

Returns:

the total number of bytes read into the buffer, or -1 is there is no more data because the end of this file has been reached.

Throws

IOException (I-§2.29)

If an I/O error occurs.

Reads up to len bytes of data from this file into an array of bytes. This method blocks until at least one byte of input is available.

Parameters:

b - the buffer into which the data is read

off - the start offset of the data

len - the maximum number of bytes read

Returns:

the total number of bytes read into the buffer, or -1 is there is no more data because the end of the file has been reached.

Throws

IOException (I-§2.29)

If an I/O error occurs.

Reads a boolean from this file. This method reads a single byte from the file. A value of 0 represents false. Any other value represents true. This method blocks until either the byte is read, the end of the stream is detected, or an exception is thrown.

Returns:

the boolean value read.

Throws

EOFException (I-§2.24)

If this file has reached the end.

Throws

IOException (I-§2.29)

If an I/O error occurs.

Reads a signed 8-bit value from this file. This method reads a byte from the file. If the byte read is b, where , then the result is

(byte)(b)
This method blocks until either the byte is read, the end of the stream is detected, or an exception is thrown.
Returns:
the next byte of this file as a signed 8-bit byte.
Throws
EOFException (I-§2.24)
If this file has reached the end.
Throws
IOException (I-§2.29)
If an I/O error occurs.

Reads a Unicode character from this file. This method reads two bytes from the file. If the bytes read, in order, are b1 and b2, where , then the result is equal to

(char)((b1 << 8) | b2)
This method blocks until either the two bytes are read, the end of the stream is detected, or an exception is thrown.
Returns:
the next two bytes of this file as an Unicode character.
Throws
EOFException (I-§2.24)
If this file reaches the end before reading two bytes.
Throws
IOException (I-§2.29)
If an I/O error occurs.

Reads a double from this file. This method reads a long value as if by the readLong method (I-§2.20.19) and then converts that long to a double using the long-Bits-To-Double method (I-§1.6.18) in class Double.

This method blocks until either the eight bytes are read, the end of the stream is detected, or an exception is thrown.

Returns:

the next eight bytes of this file, interpreted as a double.

Throws

EOFException (I-§2.24)

If this file reaches the end before reading eight bytes.

Throws

IOException (I-§2.29)

If an I/O error occurs.

Reads a float from this file. This method reads an int value as if by the readInt method (I-§2.20.17) and then converts that int to a float using the intBitsToFloat method (I-§1.7.14) in class Float.

This method blocks until either the four bytes are read, the end of the stream is detected, or an exception is thrown.

Returns:

the next four bytes of this file, interpreted as a float.

Throws

EOFException (I-§2.24)

If this file reaches the end before reading four bytes.

Throws

IOException (I-§2.29)

If an I/O error occurs.

Reads b.length bytes from this file into the byte array. This method reads repeatedly from the file until all the bytes are read. This method blocks until all the bytes are read, the end of the stream is detected, or an exception is thrown.

Parameters:

b - the buffer into which the data is read

Throws

EOFException (I-§2.24)

If this file reaches the end before reading all the bytes.

Throws

IOException (I-§2.29)

If an I/O error occurs.

Reads exactly len bytes from this file into the byte array. This method reads repeatedly from the file until all the bytes are read. This method blocks until either all the bytes are read, the end of the stream is detected, or an exception is thrown.

Parameters:

b - the buffer into which the data is read

off - the start offset of the data

len - the number of bytes to read read

Throws

EOFException (I-§2.24)

If this file reaches the end before reading all the bytes.

Throws

IOException (I-§2.29)

If an I/O error occurs.

Reads a signed 32-bit integer from this file. This method reads four bytes from the file. If the bytes read, in order, are b1, b2, b3, and b4 where , then the result is equal to

(b1 << 24) | (b2 << 16) + (b3 << 8) + b4
This method blocks until either the four bytes are read, the end of the stream is detected, or an exception is thrown.
Returns:
the next four bytes of this file, interpreted as an int.
Throws
EOFException (I-§2.24)
If this file reaches the end before reading four bytes.
Throws
IOException (I-§2.29)
If an I/O error occurs.

Reads the next line of text from this file. This method successively reads bytes from the file until it reaches the end of a line of text.

A line of text is terminated by a carriage return character ('\r'), a newline character ('\n'), a carriage return character immediately followed by a newline character, or the end of the input stream. The line-terminating character(s), if any, are included as part of the string returned.

This method blocks until either a newline character is read, a carriage return and the byte following it are read (to see if it is a newline), the end of the stream is detected, or an exception is thrown.

Returns:

the next line of text from this file.

Throws

IOException (I-§2.29)

If an I/O error occurs.

Reads a signed 64-bit integer from this file. This method reads eight bytes from the file. If the bytes read, in order, are b1, b2, b3, b4, b5, b6, b7, and b8, where

,

then the result is equal to

((long)b1 << 56) + ((long)b2 << 48)
+ ((long)b3 << 40) + ((long)b4 << 32)
+ ((long)b5 << 24) + ((long)b6 << 16)
+ ((long)b7 << 8) + b8
This method blocks until either the eight bytes are read, the end of the stream is detected, or an exception is thrown.
Returns:
the next eight bytes of this file, interpreted as a long.
Throws
EOFException (I-§2.24)
If this file reaches the end before reading eight bytes.
Throws
IOException (I-§2.29)
If an I/O error occurs.

Reads a signed 16-bit number from this file. The method reads two bytes from this file. If the two bytes read, in order, are b1 and b2, where each of the two values is between 0 and 255, inclusive, then the result is equal to:

(short)((b1 << 8) | b2)
This method blocks until either the two bytes are read, the end of the stream is detected, or an exception is thrown.
Returns:
the next two bytes of this file, interpreted as a signed 16-bit number.
Throws
EOFException (I-§2.24)
If this file reaches the end before reading two bytes.
Throws
IOException (I-§2.29)
If an I/O error occurs.

Reads an unsigned 8-bit number from this filr. This method reads a byte from this file and returns that byte

This method blocks until either the byte is read, the end of the stream is detected, or an exception is thrown.

Returns:

the next byte of this file, interpreted as an unsigned 8-bit number.

Throws

EOFException (I-§2.24)

If this file has reached the end.

Throws

IOException (I-§2.29)

If an I/O error occurs.

Reads an unsigned 16-bit number from this file. This method reads two bytes from the file. If the bytes read, in order, are b1 and b2, where , then the result is equal to

(b1 << 8) | b2
This method blocks until either the two bytes are read, the end of the stream is detected, or an exception is thrown.
Returns:
the next two bytes of this file, interprted as an unsigned 16-bit integer.
Throws
EOFException (I-§2.24)
If this file reaches the end before reading two bytes.
Throws
IOException (I-§2.29)
If an I/O error occurs.

Reads in a string from this file. The string has been encoded using a modified using a modified UTF-8 format.

The first two bytes from are read as if by readUnsignedShort (I-§2.20.22). This values gives the number of following bytes that are in the encoded string. (Note: not the length of the resuling string). The following bytes are then interpreted as bytes encoding characters in the UTF-8 format (page I-225) and are converted into characters.

This method blocks until either all the bytes are read, the end of the stream is detected, or an exception is thrown.

Returns:

a Unicode string.

Throws

EOFException (I-§2.24)

If this file reaches the end before reading all the bytes.

Throws

UTFDataFormatException (I-§2.31)

If the bytes do not represent a valid UTF-8 encoding of a Unicode string.

Throws

IOException (I-§2.29)

If an I/O error occurs.

Sets the offset from the beginning of this file at which the next read or write occurs.

Parameters:

pos - the absolute position

Throws

IOException (I-§2.29)

If an I/O error occurs.

Skips exactly n bytes of input.

This method blocks until either all the bytes are skipped, the end of the stream is detected, or an exception is thrown.

Parameters:

n - the number of bytes to be skipped

Returns:

the number of bytes skipped, which is always n.

Throws

EOFException (I-§2.24)

If this file reaches the end before skipping all the bytes.

Throws

IOException (I-§2.29)

If an I/O error occurs.

Writes b.length bytes from the specified byte array starting at offset off to this file.

Parameters:

b - the data

Throws

IOException (I-§2.29)

If an I/O error occurs.

Writes len bytes from the specified byte array starting at offset off to this file.

Parameters:

b - the data

off - the start offset in the data

len - the number of bytes to write

Throws

IOException (I-§2.29)

If an I/O error occurs.

Writes the specified byte to this file

Parameters:

b - the byte to be written

Throws

IOException (I-§2.29)

If an I/O error occurs.

Writes a boolean to the file as a one-byte value. The value true is written out as the value (byte)1; the value false is written out as the value (byte)0.

Parameters:

v - a boolean value to be written

Throws

IOException (I-§2.29)

If an I/O error occurs.

Writes out a byte to the file as a one-byte value.

Parameters:

v - a byte value to be written

Throws

IOException (I-§2.29)

If an I/O error occurs.

Writes out the string to the file as a sequence of bytes. Each character in the string is written out, in sequence, by discarding its high eight bits.

Parameters:

s - a string of bytes to be written

Throws

IOException (I-§2.29)

If an I/O error occurs.

Writes a char to the file as a two-byte value, high byte first.

Parameters:

v - a char value to be written

Throws

IOException (I-§2.29)

If an I/O error occurs.

Writes a string to the file as a sequence of characters. Each character is written to the data output stream as if by the writeChar method (I-§2.20.32).

Parameters:

s - a String value to be written

Throws

IOException (I-§2.29)

If an I/O error occurs.

Converts the double argument to a long using the doubleToLongBits method (I-§1.6.8) in class Double, and then writes that long value to the file as an eight-byte quantity, high-byte first.

Parameters:

v - a double value to be written

Throws

IOException (I-§2.29)

If an I/O error occurs.

Converts the float argument to an int using the floatToIntBits method (I-§1.7.11) in class Float, and then writes that int value to the file as a four- byte quantity, high-byte first.

Parameters:

v - a float value to be written

Throws

IOException (I-§2.29)

If an I/O error occurs.

Writes an int to the file as four bytes, high-byte first.

Parameters:

v - an int to be written

Throws

IOException (I-§2.29)

If an I/O error occurs.

Writes a long to the file as eight bytes, high-byte first.

Parameters:

v - a long to be written

Throws

IOException (I-§2.29)

If an I/O error occurs.

Writes a short to the file as two bytes, high-byte first.

Parameters:

v - a short to be written

Throws

IOException (I-§2.29)

If an I/O error occurs.

Writes out a string to the file using UTF-8 encoding in a machine-independent manner.

First, two bytes are written to the file as if by the writeShort method (I-§2.20.38) giving the number of bytes to follow. This value is the number of bytes actually written out, not the length of the string. Following the length, each character of the string is output, in sequence, using the UTF-8 encoding (page I-225) for each character.

Parameters:

str - a string to be written

Throws

IOException (I-§2.29)

If an I/O error occurs.

Packages  This Package  Prev  Next  Index