jet.util

Interface RandomInputable

All Superinterfaces:

java.io.DataInput

public interface RandomInputable
extends java.io.DataInput

The RandomInputable interface provides for reading bytes from a binary stream and skipping over bytes of the input, discarding the skipped bytes.

Method Summary

Modifier and Type	Method and Description
void	close() Closes this RandomInputable and releases any system resources associated with the input.
int	read() Reads the next byte of data from the RandomInputable.
int	read(byte[] b) Reads some number of bytes from the RandomInputable and stores them into the buffer array b.
int	read(byte[] b, int off, int len) Reads at most len bytes of data from the RandomInputable into an array of bytes.
void	saveTo(java.lang.String filename) Saves all contents of RandomInputable into a destination file.
int	skipBytes(int n) Attempts to skip over n bytes of the input, discarding the skipped bytes.

Methods inherited from interface java.io.DataInput

readBoolean, readByte, readChar, readDouble, readFloat, readFully, readFully, readInt, readLine, readLong, readShort, readUnsignedByte, readUnsignedShort, readUTF

Method Detail

close

void close()
    throws java.io.IOException

Closes this RandomInputable and releases any system resources associated with the input.

Throws:

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

read

int read()
  throws java.io.IOException

Reads the next byte of data from the RandomInputable. The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream is reached, the value -1 will be returned. This method is blocked until the input data is available, the end of the stream is detected, or an exception is thrown.

Returns:

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

Throws:

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

read

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

Reads at most len bytes of data from the RandomInputable into an array of bytes. An attempt is made to read as many as len bytes, but a smaller number may be read. The number of bytes actually read is returned as an integer.

This method is blocked until the input data is available, the end of the file is detected, or an exception is thrown.

If the len is zero, then no bytes will be read and 0 will be returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at the end of the file, the value -1 will be returned; otherwise, at least one byte will be read and stored into b.

The first byte read is stored into element b[off], the next one into b[off+1], and so on. The number of bytes read is, at most, equal to len. Let k be the number of bytes actually read; these bytes will be stored in elements b[off] through b[off+k-1], leaving elements b[off+k] through b[off+len-1] unaffected.

In every case, elements b[0] through b[off] and elements b[off+len] through b[b.length-1] are unaffected.

The read(b, off, len) method for class RandomInputable simply calls the method read() repeatedly. If the first call results in an IOException, that exception will be returned from the call to the read(b, off, len) method. If any subsequent call to read() results in an IOException, the exception will be caught and treated as if it were the end of the file; the bytes read up to that point are stored into b and the number of bytes read before the exception occurred is returned. The default implementation of this method is blocked until the requested amount of input data len is read, the end of the file is detected, or an exception is thrown. Subclasses are encouraged to provide a more efficient implementation of this method.

Parameters:

b - The buffer into which the data is read.

off - The start offset in array b at which the data is written.

len - The maximum number of bytes to be read.

Returns:

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

Throws:

java.io.IOException - if the first byte cannot be read for any reason other than reaching the end of the file, or if the input stream is closed, or if some other I/O error occurs.

java.lang.NullPointerException - if b is null.

java.lang.IndexOutOfBoundsException - if off is negative, len is negative, or len is greater than b.length - off.

read

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

Reads some number of bytes from the RandomInputable and stores them into the buffer array b. The number of bytes actually read is returned as an integer. This method is blocked until the input data is available, the end of the file is detected, or an exception is thrown.

If the length of b is zero, then no bytes will be read and 0 will be returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at the end of the file, the value -1 will be returned; otherwise, at least one byte will be read and stored into b.

The first byte read is stored into element b[0], the next one into b[1], and so on. The number of bytes read is, at most, equal to the length of b. Let k be the number of bytes actually read; these bytes will be stored in elements b[0] through b[k-1], leaving elements b[k] through b[b.length-1] unaffected.

The read(b) method for class RandomInputable has the same effect as:

 read(b, 0, b.length) .

Parameters:

b - The buffer into which the data is read.

Returns:

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

Throws:

java.io.IOException - if the first byte cannot be read for any reason other than reaching the end of the file, or if the input stream is closed, or if some other I/O error occurs.

java.lang.NullPointerException - if b is null.

saveTo

void saveTo(java.lang.String filename)
     throws java.io.IOException

Saves all contents of RandomInputable into a destination file.

Parameters:

filename - Destination file string.

Throws:

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

skipBytes

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

Attempts to skip over n bytes of the input, discarding the skipped bytes.

This method may skip over some smaller number of bytes, possibly zero. This may result from any of a number of conditions; reaching the end of the file before n bytes is skipped is only one possibility. This method never throws an EOFException. The actual number of bytes skipped is returned. If n is negative, no bytes are skipped.

Specified by:

skipBytes in interface java.io.DataInput

Parameters:

n - The number of bytes to be skipped.

Returns:

the actual number of bytes skipped.

Throws:

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