ucar.unidata.io
Class RandomAccessFile

java.lang.Object
  ucar.unidata.io.RandomAccessFile

All Implemented Interfaces:

java.io.DataInput, java.io.DataOutput

Direct Known Subclasses:

HTTPRandomAccessFile, HTTPRandomAccessFile2, HTTPRandomAccessFile3, InMemoryRandomAccessFile, MMapRandomAccessFile

public class RandomAccessFile
extends java.lang.Object
implements java.io.DataInput, java.io.DataOutput

RandomAccessFile.java. By Russ Rew, based on BufferedRandomAccessFile by Alex McManus, based on Sun's source code for java.io.RandomAccessFile. For Alex McManus version from which this derives, see his Freeware Java Classes. A buffered drop-in replacement for java.io.RandomAccessFile. Instances of this class realise substantial speed increases over java.io.RandomAccessFile through the use of buffering. This is a subclass of Object, as it was not possible to subclass java.io.RandomAccessFile because many of the methods are final. However, if it is necessary to use RandomAccessFile and java.io.RandomAccessFile interchangeably, both classes implement the DataInput and DataOutput interfaces.

Author:

Alex McManus, Russ Rew, john caron

See Also:

DataInput, DataOutput, RandomAccessFile

Field Summary

static int	BIG_ENDIAN _more_
protected boolean	bigEndian The current endian (big or little) mode of the file.
protected byte[]	buffer The buffer used to load the data.
protected long	bufferStart The offset in bytes of the start of the buffer, from the start of the file.
protected boolean	cached Support for ucar.unidata.io.FileCache.
protected long	dataEnd The offset in bytes of the end of the data in the buffer, from the start of the file.
protected int	dataSize The size of the data stored in the buffer, in bytes.
protected static boolean	debugAccess
protected static boolean	debugLeaks _more_
protected static int	defaultBufferSize The default buffer size, in bytes.
protected boolean	endOfFile True if we are at the end of the file.
protected java.io.RandomAccessFile	file The underlying java.io.RandomAccessFile.
protected long	filePosition The offset in bytes from the file start, of the next read or write operation.
static int	LITTLE_ENDIAN _more_
protected java.lang.String	location _more_
static java.util.List	openFiles _more_
protected boolean	readonly The access mode of the file.

Constructor Summary

protected	RandomAccessFile(int bufferSize) _more_
	RandomAccessFile(java.lang.String location, java.lang.String mode) Constructor, default buffer size.
	RandomAccessFile(java.lang.String location, java.lang.String mode, int bufferSize) Constructor.

Method Summary

void	close() Close the file, and release any associated system resources.
void	flush() Copy the contents of the buffer to the disk.
java.io.FileDescriptor	getFD() Returns the opaque file descriptor object associated with this file.
long	getFilePointer() Returns the current position in the file, where the next read or write will occur.
java.lang.String	getLocation() Get the file location, or name.
java.io.RandomAccessFile	getRandomAccessFile() Allow access to the underlying java.io.RandomAccessFile.
boolean	isAtEndOfFile() Return true if file pointer is at end of file.
boolean	isCached() Find whether this fie is in the cache.
long	length() Get the length of the file.
void	order(int endian) Change the current endian mode.
protected int	read_(long pos, byte[] b, int offset, int len) read directly, without going through the buffer
int	read() Read a byte of data from the file, blocking until data is available.
int	read(byte[] b) Read up to b.length( ) bytes into an array.
int	read(byte[] b, int off, int len) Read up to len bytes into an array, at a specified offset.
boolean	readBoolean() Reads a boolean from this file.
byte	readByte() Reads a signed 8-bit value from this file.
protected int	readBytes(byte[] b, int off, int len) Read up to len bytes into an array, at a specified offset.
char	readChar() Reads a Unicode character from this file.
double	readDouble() Reads a double from this file.
void	readDouble(double[] pa, int start, int n) _more_
float	readFloat() Reads a float from this file.
void	readFloat(float[] pa, int start, int n) _more_
void	readFully(byte[] b) Reads b.length bytes from this file into the byte array.
void	readFully(byte[] b, int off, int len) Reads exactly len bytes from this file into the byte array.
int	readInt() Reads a signed 32-bit integer from this file.
void	readInt(int[] pa, int start, int n) Reads a signed 24-bit integer from this file.
int	readIntUnbuffered(long pos) Read an integer at the given position, bypassing all buffering.
java.lang.String	readLine() Reads the next line of text from this file.
long	readLong() Reads a signed 64-bit integer from this file.
void	readLong(long[] pa, int start, int n) _more_
short	readShort() Reads a signed 16-bit number from this file.
void	readShort(short[] pa, int start, int n) _more_
java.lang.String	readString(int nbytes) Read a String of knoen length.
int	readUnsignedByte() Reads an unsigned 8-bit number from this file.
int	readUnsignedShort() Reads an unsigned 16-bit number from this file.
java.lang.String	readUTF() Reads in a string from this file.
void	seek(long pos) Set the position in the file for the next read or write.
void	setCached(boolean cached) Set whether this fie is in the cache.
static void	setDebugAccess(boolean b) Debugging, do not use.
static void	setDebugLeaks(boolean b) Debugging, do not use.
void	setExtendMode() Set extendMode for truncated, yet valid files - old NetCDF code allowed this when NOFILL on, and user doesnt write all variables.
void	setMinLength(long minLength) Make sure file is at least this long when its closed.
int	skipBytes(int n) Skips exactly n bytes of input.
void	synch() _more_
java.lang.String	toString() Create a string representation of this object.
void	unread() Unread the last byte read.
void	write(byte[] b) Writes b.length bytes from the specified byte array starting at offset off to this file.
void	write(byte[] b, int off, int len) Writes len bytes from the specified byte array starting at offset off to this file.
void	write(int b) Write a byte to the file.
void	writeBoolean(boolean v) Writes a boolean to the file as a 1-byte value.
void	writeBoolean(boolean[] pa, int start, int n) _more_
void	writeByte(int v) Writes a byte to the file as a 1-byte value.
void	writeBytes(byte[] b, int off, int len) Write len bytes from an array to the file.
void	writeBytes(char[] b, int off, int len) Writes the character array to the file as a sequence of bytes.
void	writeBytes(java.lang.String s) Writes the string to the file as a sequence of bytes.
void	writeChar(char[] pa, int start, int n) _more_
void	writeChar(int v) Writes a char to the file as a 2-byte value, high byte first.
void	writeChars(java.lang.String s) Writes a string to the file as a sequence of characters.
void	writeDouble(double v) Converts the double argument to a long using the doubleToLongBits method in class Double, and then writes that long value to the file as an 8-byte quantity, high byte first.
void	writeDouble(double[] pa, int start, int n) _more_
void	writeFloat(float v) Converts the float argument to an int using the floatToIntBits method in class Float, and then writes that int value to the file as a 4-byte quantity, high byte first.
void	writeFloat(float[] pa, int start, int n) _more_
void	writeInt(int v) Writes an int to the file as four bytes, high byte first.
void	writeInt(int[] pa, int start, int n) _more_
void	writeLong(long v) Writes a long to the file as eight bytes, high byte first.
void	writeLong(long[] pa, int start, int n) _more_
void	writeShort(int v) Writes a short to the file as two bytes, high byte first.
void	writeShort(short[] pa, int start, int n) _more_
void	writeUTF(java.lang.String str) Writes a string to the file using UTF-8 encoding in a machine-independent manner.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

BIG_ENDIAN

public static final int BIG_ENDIAN

_more_

See Also:

Constant Field Values

LITTLE_ENDIAN

public static final int LITTLE_ENDIAN

_more_

See Also:

Constant Field Values

debugLeaks

protected static boolean debugLeaks

_more_

debugAccess

protected static boolean debugAccess

openFiles

public static java.util.List openFiles

_more_

defaultBufferSize

protected static final int defaultBufferSize

The default buffer size, in bytes.

See Also:

Constant Field Values

location

protected java.lang.String location

_more_

file

protected java.io.RandomAccessFile file

The underlying java.io.RandomAccessFile.

filePosition

protected long filePosition

The offset in bytes from the file start, of the next read or write operation.

buffer

protected byte[] buffer

The buffer used to load the data.

bufferStart

protected long bufferStart

The offset in bytes of the start of the buffer, from the start of the file.

dataEnd

protected long dataEnd

The offset in bytes of the end of the data in the buffer, from the start of the file. This can be calculated from bufferStart + dataSize, but it is cached to speed up the read( ) method.

dataSize

protected int dataSize

The size of the data stored in the buffer, in bytes. This may be less than the size of the buffer.

endOfFile

protected boolean endOfFile

True if we are at the end of the file.

readonly

protected boolean readonly

The access mode of the file.

bigEndian

protected boolean bigEndian

The current endian (big or little) mode of the file.

cached

protected boolean cached

Support for ucar.unidata.io.FileCache.

Constructor Detail

RandomAccessFile

protected RandomAccessFile(int bufferSize)

_more_

Parameters:

bufferSize - _more_

RandomAccessFile

public RandomAccessFile(java.lang.String location,
                        java.lang.String mode)
                 throws java.io.IOException

Constructor, default buffer size.

Parameters:

location - location of the file

mode - same as for java.io.RandomAccessFile

Throws:

java.io.IOException

RandomAccessFile

public RandomAccessFile(java.lang.String location,
                        java.lang.String mode,
                        int bufferSize)
                 throws java.io.IOException

Constructor.

Parameters:

location - location of the file

mode - same as for java.io.RandomAccessFile

bufferSize - size of buffer to use.

Throws:

java.io.IOException

Method Detail

setDebugLeaks

public static void setDebugLeaks(boolean b)

Debugging, do not use.

setDebugAccess

public static void setDebugAccess(boolean b)

Debugging, do not use.

getRandomAccessFile

public java.io.RandomAccessFile getRandomAccessFile()

Allow access to the underlying java.io.RandomAccessFile. WARNING! BROKEN ENCAPSOLATION, DO NOT USE. May change implementation in the future.

Returns:

the underlying java.io.RandomAccessFile.

close

public void close()
           throws java.io.IOException

Close the file, and release any associated system resources.

Throws:

java.io.IOException - if an I/O error occurrs.

isAtEndOfFile

public boolean isAtEndOfFile()

Return true if file pointer is at end of file.

Returns:

_more_

seek

public void seek(long pos)
          throws java.io.IOException

Set the position in the file for the next read or write.

Parameters:

pos - the offset (in bytes) from the start of the file.

Throws:

java.io.IOException - if an I/O error occurrs.

getFilePointer

public long getFilePointer()
                    throws java.io.IOException

Returns the current position in the file, where the next read or write will occur.

Returns:

the offset from the start of the file in bytes.

Throws:

java.io.IOException - if an I/O error occurrs.

getLocation

public java.lang.String getLocation()

Get the file location, or name.

Returns:

_more_

length

public long length()
            throws java.io.IOException

Get the length of the file. The data in the buffer (which may not have been written the disk yet) is taken into account.

Returns:

the length of the file in bytes.

Throws:

java.io.IOException - if an I/O error occurrs.

order

public void order(int endian)

Change the current endian mode. Subsequent reads of short, int, float, double, long, char will use this. Does not currently affect writes. Default values is BIG_ENDIAN.

Parameters:

endian - BIG_ENDIAN or LITTLE_ENDIAN

getFD

public java.io.FileDescriptor getFD()
                             throws java.io.IOException

Returns the opaque file descriptor object associated with this file.

Returns:

the file descriptor object associated with this file.

Throws:

java.io.IOException - if an I/O error occurs.

flush

public void flush()
           throws java.io.IOException

Copy the contents of the buffer to the disk.

Throws:

java.io.IOException - if an I/O error occurrs.

setMinLength

public void setMinLength(long minLength)

Make sure file is at least this long when its closed. needed when not using fill mode, and not all data is written.

Parameters:

minLength - minimum length of the file.

setExtendMode

public void setExtendMode()

Set extendMode for truncated, yet valid files - old NetCDF code allowed this when NOFILL on, and user doesnt write all variables.

read

public int read()
         throws java.io.IOException

Read a byte of data from the file, blocking until data is available.

Returns:

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

Throws:

java.io.IOException - if an I/O error occurrs.

readBytes

protected int readBytes(byte[] b,
                        int off,
                        int len)
                 throws java.io.IOException

Read up to len bytes into an array, at a specified offset. This will block until at least one byte has been read.

Parameters:

b - the byte array to receive the bytes.

off - the offset in the array where copying will start.

len - the number of bytes to copy.

Returns:

the actual number of bytes read, or -1 if there is not more data due to the end of the file being reached.

Throws:

java.io.IOException - if an I/O error occurrs.

read_

protected int read_(long pos,
                    byte[] b,
                    int offset,
                    int len)
             throws java.io.IOException

read directly, without going through the buffer

Parameters:

pos - _more_

b - _more_

offset - _more_

len - _more_

Returns:

_more_

Throws:

java.io.IOException - _more_

read

public int read(byte[] b,
                int off,
                int len)
         throws java.io.IOException

Read up to len bytes into an array, at a specified offset. This will block until at least one byte has been read.

Parameters:

b - the byte array to receive the bytes.

off - the offset in the array where copying will start.

len - the number of bytes to copy.

Returns:

the actual number of bytes read, or -1 if there is not more data due to the end of the file being reached.

Throws:

java.io.IOException - if an I/O error occurrs.

read

public int read(byte[] b)
         throws java.io.IOException

Read up to b.length( ) bytes into an array. This will block until at least one byte has been read.

Parameters:

b - the byte array to receive the bytes.

Returns:

the actual number of bytes read, or -1 if there is not more data due to the end of the file being reached.

Throws:

java.io.IOException - if an I/O error occurrs.

readFully

public final void readFully(byte[] b)
                     throws java.io.IOException

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.

Specified by:

readFully in interface java.io.DataInput

Parameters:

b - the buffer into which the data is read.

Throws:

java.io.EOFException - if this file reaches the end before reading all the bytes.

java.io.IOException - if an I/O error occurs.

readFully

public final void readFully(byte[] b,
                            int off,
                            int len)
                     throws java.io.IOException

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 all the bytes are read, the end of the stream is detected, or an exception is thrown.

Specified by:

readFully in interface java.io.DataInput

Parameters:

b - the buffer into which the data is read.

off - the start offset of the data.

len - the number of bytes to read.

Throws:

java.io.EOFException - if this file reaches the end before reading all the bytes.

java.io.IOException - if an I/O error occurs.

skipBytes

public int skipBytes(int n)
              throws java.io.IOException

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

Specified by:

skipBytes in interface java.io.DataInput

Parameters:

n - the number of bytes to be skipped.

Returns:

the number of bytes skipped, which is always n.

Throws:

java.io.EOFException - if this file reaches the end before skipping all the bytes.

java.io.IOException - if an I/O error occurs.

unread

public void unread()

Unread the last byte read. This method should not be used more than once between reading operations, or strange things might happen.

write

public void write(int b)
           throws java.io.IOException

Write a byte to the file. If the file has not been opened for writing, an IOException will be raised only when an attempt is made to write the buffer to the file.

Caveat: the effects of seek( )ing beyond the end of the file are undefined.

Specified by:

write in interface java.io.DataOutput

Parameters:

b - _more_

Throws:

java.io.IOException - if an I/O error occurrs.

writeBytes

public void writeBytes(byte[] b,
                       int off,
                       int len)
                throws java.io.IOException

Write len bytes from an array to the file.

Parameters:

b - the array containing the data.

off - the offset in the array to the data.

len - the length of the data.

Throws:

java.io.IOException - if an I/O error occurrs.

write

public void write(byte[] b)
           throws java.io.IOException

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

Specified by:

write in interface java.io.DataOutput

Parameters:

b - the data.

Throws:

java.io.IOException - if an I/O error occurs.

write

public void write(byte[] b,
                  int off,
                  int len)
           throws java.io.IOException

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

Specified by:

write in interface java.io.DataOutput

Parameters:

b - the data.

off - the start offset in the data.

len - the number of bytes to write.

Throws:

java.io.IOException - if an I/O error occurs.

readBoolean

public final boolean readBoolean()
                          throws java.io.IOException

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 the byte is read, the end of the stream is detected, or an exception is thrown.

Specified by:

readBoolean in interface java.io.DataInput

Returns:

the boolean value read.

Throws:

java.io.EOFException - if this file has reached the end.

java.io.IOException - if an I/O error occurs.

readByte

public final byte readByte()
                    throws java.io.IOException

Reads a signed 8-bit value from this file. This method reads a byte from the file. If the byte read is b, where 0 <= b <= 255, then the result is:

(byte)(b)

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

Specified by:

readByte in interface java.io.DataInput

Returns:

the next byte of this file as a signed 8-bit byte.

Throws:

java.io.EOFException - if this file has reached the end.

java.io.IOException - if an I/O error occurs.

readUnsignedByte

public final int readUnsignedByte()
                           throws java.io.IOException

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

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

Specified by:

readUnsignedByte in interface java.io.DataInput

Returns:

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

Throws:

java.io.EOFException - if this file has reached the end.

java.io.IOException - if an I/O error occurs.

readShort

public final short readShort()
                      throws java.io.IOException

Reads a signed 16-bit number from this file. The method reads 2 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 the two bytes are read, the end of the stream is detected, or an exception is thrown.

Specified by:

readShort in interface java.io.DataInput

Returns:

the next two bytes of this file, interpreted as a signed 16-bit number.

Throws:

java.io.EOFException - if this file reaches the end before reading two bytes.

java.io.IOException - if an I/O error occurs.

readShort

public final void readShort(short[] pa,
                            int start,
                            int n)
                     throws java.io.IOException

_more_

Parameters:

pa - _more_

start - _more_

n - _more_

Throws:

java.io.IOException - _more_

readUnsignedShort

public final int readUnsignedShort()
                            throws java.io.IOException

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 0 <= b1, b2 <= 255, then the result is equal to:

(b1 << 8) | b2

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

Specified by:

readUnsignedShort in interface java.io.DataInput

Returns:

the next two bytes of this file, interpreted as an unsigned 16-bit integer.

Throws:

java.io.EOFException - if this file reaches the end before reading two bytes.

java.io.IOException - if an I/O error occurs.

readChar

public final char readChar()
                    throws java.io.IOException

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 0 <= b1, b2 <= 255, then the result is equal to:

(char)((b1 << 8) | b2)

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

Specified by:

readChar in interface java.io.DataInput

Returns:

the next two bytes of this file as a Unicode character.

Throws:

java.io.EOFException - if this file reaches the end before reading two bytes.

java.io.IOException - if an I/O error occurs.

readInt

public final int readInt()
                  throws java.io.IOException

Reads a signed 32-bit integer from this file. This method reads 4 bytes from the file. If the bytes read, in order, are b1, b2, b3, and b4, where 0 <= b1, b2, b3, b4 <= 255, then the result is equal to:

(b1 << 24) | (b2 << 16) + (b3 << 8) + b4

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

Specified by:

readInt in interface java.io.DataInput

Returns:

the next four bytes of this file, interpreted as an int.

Throws:

java.io.EOFException - if this file reaches the end before reading four bytes.

java.io.IOException - if an I/O error occurs.

readIntUnbuffered

public final int readIntUnbuffered(long pos)
                            throws java.io.IOException

Read an integer at the given position, bypassing all buffering.

Parameters:

pos - read a byte at this position

Returns:

The int that was read

Throws:

java.io.IOException

readInt

public final void readInt(int[] pa,
                          int start,
                          int n)
                   throws java.io.IOException

Reads a signed 24-bit integer from this file. This method reads 3 bytes from the file. If the bytes read, in order, are b1, b2, and b3, where 0 <= b1, b2, b3 <= 255, then the result is equal to:

(b1 << 16) | (b2 << 8) + (b3 << 0)

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

Parameters:

pa - _more_

start - _more_

n - _more_

Throws:

java.io.EOFException - if this file reaches the end before reading four bytes.

java.io.IOException - if an I/O error occurs.

readLong

public final long readLong()
                    throws java.io.IOException

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:

0 <= b1, b2, b3, b4, b5, b6, b7, b8 <=255,

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 the eight bytes are read, the end of the stream is detected, or an exception is thrown.

Specified by:

readLong in interface java.io.DataInput

Returns:

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

Throws:

java.io.EOFException - if this file reaches the end before reading eight bytes.

java.io.IOException - if an I/O error occurs.

readLong

public final void readLong(long[] pa,
                           int start,
                           int n)
                    throws java.io.IOException

_more_

Parameters:

pa - _more_

start - _more_

n - _more_

Throws:

java.io.IOException - _more_

readFloat

public final float readFloat()
                      throws java.io.IOException

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

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

Specified by:

readFloat in interface java.io.DataInput

Returns:

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

Throws:

java.io.EOFException - if this file reaches the end before reading four bytes.

java.io.IOException - if an I/O error occurs.

See Also:

RandomAccessFile.readInt(), Float.intBitsToFloat(int)

readFloat

public final void readFloat(float[] pa,
                            int start,
                            int n)
                     throws java.io.IOException

_more_

Parameters:

pa - _more_

start - _more_

n - _more_

Throws:

java.io.IOException - _more_

readDouble

public final double readDouble()
                        throws java.io.IOException

Reads a double from this file. This method reads a long value as if by the readLong method and then converts that long to a double using the longBitsToDouble method in class Double.

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

Specified by:

readDouble in interface java.io.DataInput

Returns:

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

Throws:

java.io.EOFException - if this file reaches the end before reading eight bytes.

java.io.IOException - if an I/O error occurs.

See Also:

RandomAccessFile.readLong(), Double.longBitsToDouble(long)

readDouble

public final void readDouble(double[] pa,
                             int start,
                             int n)
                      throws java.io.IOException

_more_

Parameters:

pa - _more_

start - _more_

n - _more_

Throws:

java.io.IOException - _more_

readLine

public final java.lang.String readLine()
                                throws java.io.IOException

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 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.

Specified by:

readLine in interface java.io.DataInput

Returns:

the next line of text from this file.

Throws:

java.io.IOException - if an I/O error occurs.

readUTF

public final java.lang.String readUTF()
                               throws java.io.IOException

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

The first two bytes are read as if by readUnsignedShort. This value gives the number of following bytes that are in the encoded string, not the length of the resulting string. The following bytes are then interpreted as bytes encoding characters in the UTF-8 format and are converted into characters.

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

Specified by:

readUTF in interface java.io.DataInput

Returns:

a Unicode string.

Throws:

java.io.EOFException - if this file reaches the end before reading all the bytes.

java.io.IOException - if an I/O error occurs.

java.io.UTFDataFormatException - if the bytes do not represent valid UTF-8 encoding of a Unicode string.

See Also:

RandomAccessFile.readUnsignedShort()

readString

public java.lang.String readString(int nbytes)
                            throws java.io.IOException

Read a String of knoen length.

Parameters:

nbytes - number of bytes to read

Returns:

String wrapping the bytes.

Throws:

java.io.IOException

writeBoolean

public final void writeBoolean(boolean v)
                        throws java.io.IOException

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

Specified by:

writeBoolean in interface java.io.DataOutput

Parameters:

v - a boolean value to be written.

Throws:

java.io.IOException - if an I/O error occurs.

writeBoolean

public final void writeBoolean(boolean[] pa,
                               int start,
                               int n)
                        throws java.io.IOException

_more_

Parameters:

pa - _more_

start - _more_

n - _more_

Throws:

java.io.IOException - _more_

writeByte

public final void writeByte(int v)
                     throws java.io.IOException

Writes a byte to the file as a 1-byte value.

Specified by:

writeByte in interface java.io.DataOutput

Parameters:

v - a byte value to be written.

Throws:

java.io.IOException - if an I/O error occurs.

writeShort

public final void writeShort(int v)
                      throws java.io.IOException

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

Specified by:

writeShort in interface java.io.DataOutput

Parameters:

v - a short to be written.

Throws:

java.io.IOException - if an I/O error occurs.

writeShort

public final void writeShort(short[] pa,
                             int start,
                             int n)
                      throws java.io.IOException

_more_

Parameters:

pa - _more_

start - _more_

n - _more_

Throws:

java.io.IOException - _more_

writeChar

public final void writeChar(int v)
                     throws java.io.IOException

Writes a char to the file as a 2-byte value, high byte first.

Specified by:

writeChar in interface java.io.DataOutput

Parameters:

v - a char value to be written.

Throws:

java.io.IOException - if an I/O error occurs.

writeChar

public final void writeChar(char[] pa,
                            int start,
                            int n)
                     throws java.io.IOException

_more_

Parameters:

pa - _more_

start - _more_

n - _more_

Throws:

java.io.IOException - _more_

writeInt

public final void writeInt(int v)
                    throws java.io.IOException

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

Specified by:

writeInt in interface java.io.DataOutput

Parameters:

v - an int to be written.

Throws:

java.io.IOException - if an I/O error occurs.

writeInt

public final void writeInt(int[] pa,
                           int start,
                           int n)
                    throws java.io.IOException

_more_

Parameters:

pa - _more_

start - _more_

n - _more_

Throws:

java.io.IOException - _more_

writeLong

public final void writeLong(long v)
                     throws java.io.IOException

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

Specified by:

writeLong in interface java.io.DataOutput

Parameters:

v - a long to be written.

Throws:

java.io.IOException - if an I/O error occurs.

writeLong

public final void writeLong(long[] pa,
                            int start,
                            int n)
                     throws java.io.IOException

_more_

Parameters:

pa - _more_

start - _more_

n - _more_

Throws:

java.io.IOException - _more_

writeFloat

public final void writeFloat(float v)
                      throws java.io.IOException

Converts the float argument to an int using the floatToIntBits method in class Float, and then writes that int value to the file as a 4-byte quantity, high byte first.

Specified by:

writeFloat in interface java.io.DataOutput

Parameters:

v - a float value to be written.

Throws:

java.io.IOException - if an I/O error occurs.

See Also:

Float.floatToIntBits(float)

writeFloat

public final void writeFloat(float[] pa,
                             int start,
                             int n)
                      throws java.io.IOException

_more_

Parameters:

pa - _more_

start - _more_

n - _more_

Throws:

java.io.IOException - _more_

writeDouble

public final void writeDouble(double v)
                       throws java.io.IOException

Converts the double argument to a long using the doubleToLongBits method in class Double, and then writes that long value to the file as an 8-byte quantity, high byte first.

Specified by:

writeDouble in interface java.io.DataOutput

Parameters:

v - a double value to be written.

Throws:

java.io.IOException - if an I/O error occurs.

See Also:

Double.doubleToLongBits(double)

writeDouble

public final void writeDouble(double[] pa,
                              int start,
                              int n)
                       throws java.io.IOException

_more_

Parameters:

pa - _more_

start - _more_

n - _more_

Throws:

java.io.IOException - _more_

writeBytes

public final void writeBytes(java.lang.String s)
                      throws java.io.IOException

Writes 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.

Specified by:

writeBytes in interface java.io.DataOutput

Parameters:

s - a string of bytes to be written.

Throws:

java.io.IOException - if an I/O error occurs.

writeBytes

public final void writeBytes(char[] b,
                             int off,
                             int len)
                      throws java.io.IOException

Writes the character array 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:

b - a character array of bytes to be written.

off - the index of the first character to write.

len - the number of characters to write.

Throws:

java.io.IOException - if an I/O error occurs.

writeChars

public final void writeChars(java.lang.String s)
                      throws java.io.IOException

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.

Specified by:

writeChars in interface java.io.DataOutput

Parameters:

s - a String value to be written.

Throws:

java.io.IOException - if an I/O error occurs.

See Also:

RandomAccessFile.writeChar(int)

writeUTF

public final void writeUTF(java.lang.String str)
                    throws java.io.IOException

Writes 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 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 for each character.

Specified by:

writeUTF in interface java.io.DataOutput

Parameters:

str - a string to be written.

Throws:

java.io.IOException - if an I/O error occurs.

toString

public java.lang.String toString()

Create a string representation of this object.

Overrides:

toString in class java.lang.Object

Returns:

a string representation of the state of the object.

setCached

public void setCached(boolean cached)

Set whether this fie is in the cache.

Parameters:

cached - in the cache or not.

See Also:

FileCache

isCached

public boolean isCached()

Find whether this fie is in the cache.

Returns:

true if in the cache.

See Also:

FileCache

synch

public void synch()
           throws java.io.IOException

_more_

Throws:

java.io.IOException - _more_