Top Description Fields Constructors Methods
org.hsqldb.lib

public final Class CountdownInputStream

extends InputStream
Class Inheritance
Imports
java.io.IOException, .InputStream

Counts down from a specified value the number of bytes actually read from the wrapped InputStream.

Returns minus one (-1) early from readXXX methods if the count down reaches zero (0) before the end of the wrapped InputStream is encountered.

This class is especially useful when a fixed number of bytes is to be read from an InputStream that is in turn to be used as the source for an InputStreamReader.

Author
Campbell Burnet (campbell-burnet@users dot sourceforge.net)
Since
1.9.0
Version
2.1.1

Field Summary

Modifier and TypeField and Description
private long
private InputStream

Constructor Summary

AccessConstructor and Description
public

Method Summary

Modifier and TypeMethod and Description
public int
available()

Overrides java.io.InputStream.available.

Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking, which may be 0, or 0 when end of stream is detected.

public void
close()

Overrides java.io.InputStream.close.

Implements java.io.Closeable.close.

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

public long
public int
read()

Implements abstract java.io.InputStream.read.

Reads the next byte of data from the input stream.

public int
read(final byte[] buf)

Overrides java.io.InputStream.read.

Reads some number of bytes from the input stream and stores them into the buffer array b.

public int
read(final byte[] buf, final int off, int len)

Overrides java.io.InputStream.read.

Reads up to len bytes of data from the input stream into an array of bytes.

public void
setCount(long count)

public long
skip(long count)

Overrides java.io.InputStream.skip.

Skips over and discards n bytes of data from this input stream.

Inherited from java.io.InputStream:
markmarkSupportednullInputStreamreadAllBytesreadNBytesreadNBytesresetskipNBytestransferTo

Field Detail

m_countback to summary
private long m_count
m_inputback to summary
private InputStream m_input

Constructor Detail

CountdownInputStreamback to summary
public CountdownInputStream(final InputStream is)

Method Detail

availableback to summary
public int available() throws IOException

Overrides java.io.InputStream.available.

Doc from java.io.InputStream.available.

Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking, which may be 0, or 0 when end of stream is detected. The read might be on the same thread or another thread. A single read or skip of this many bytes will not block, but may read or skip fewer bytes.

Note that while some implementations of InputStream will return the total number of bytes in the stream, many will not. It is never correct to use the return value of this method to allocate a buffer intended to hold all data in this stream.

A subclass's implementation of this method may choose to throw an IOException if this input stream has been closed by invoking the close() method.

Exceptions
IOException:
if an I/O error occurs.
closeback to summary
public void close() throws IOException

Overrides java.io.InputStream.close.

Implements java.io.Closeable.close.

Doc from java.io.InputStream.close.

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

Exceptions
IOException:
if an I/O error occurs.
getCountback to summary
public long getCount()
readback to summary
public int read() throws IOException

Implements abstract java.io.InputStream.read.

Doc from java.io.InputStream.read.

Reads the next byte of data from the input stream. 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 has been reached, the value -1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.

Exceptions
IOException:
if an I/O error occurs.
readback to summary
public int read(final byte[] buf) throws IOException

Overrides java.io.InputStream.read.

Doc from java.io.InputStream.read.

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

If the length of b is zero, then no bytes are read and 0 is 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 is returned; otherwise, at least one byte is 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.

Exceptions
IOException:
If the first byte cannot be read for any reason other than the end of the file, if the input stream has been closed, or if some other I/O error occurs.
readback to summary
public int read(final byte[] buf, final int off, int len) throws IOException

Overrides java.io.InputStream.read.

Doc from java.io.InputStream.read.

Reads up to len bytes of data from the input stream 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 blocks until input data is available, end of file is detected, or an exception is thrown.

If len is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value -1 is returned; otherwise, at least one byte is 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-1] and elements b[off+len] through b[b.length-1] are unaffected.

Exceptions
IOException:
If the first byte cannot be read for any reason other than end of file, or if the input stream has been closed, or if some other I/O error occurs.
setCountback to summary
public void setCount(long count)
skipback to summary
public long skip(long count) throws IOException

Overrides java.io.InputStream.skip.

Doc from java.io.InputStream.skip.

Skips over and discards n bytes of data from this input stream. The skip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly 0. This may result from any of a number of conditions; reaching end of file before n bytes have been skipped is only one possibility. The actual number of bytes skipped is returned. If n is negative, the skip method for class InputStream always returns 0, and no bytes are skipped. Subclasses may handle the negative value differently.

Exceptions
IOException:
if an I/O error occurs.