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FlexDoc/Javadoc 2.0 Demo Java Doc |
Applications that need to define a subclass of InputStream must always provide a method that returns the next byte of input.
Constructor Summary |
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Constructor for subclasses to call.
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Method Summary |
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int |
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.
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void |
close()
Closes this input stream and releases any system resources associated
with the stream.
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void |
mark(int readlimit)
Marks the current position in this input stream.
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boolean |
Tests if this input stream supports the mark and
reset methods.
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static InputStream |
Returns a new InputStream that reads no bytes.
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abstract int |
read()
Reads the next byte of data from the input stream.
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int |
read(byte[] b)
Reads some number of bytes from the input stream and stores them into
the buffer array b.
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int |
read(byte[] b, int off, int len)
Reads up to len bytes of data from the input stream into
an array of bytes.
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byte[] |
Reads all remaining bytes from the input stream.
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int |
readNBytes(byte[] b, int off, int len)
Reads the requested number of bytes from the input stream into the given
byte array.
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byte[] |
readNBytes(int len)
Reads up to a specified number of bytes from the input stream.
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void |
reset()
Repositions this stream to the position at the time the
mark method was last called on this input stream.
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long |
skip(long n)
Skips over and discards n bytes of data from this input
stream.
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void |
skipNBytes(long n)
Skips over and discards exactly n bytes of data from this input
stream.
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long |
transferTo(OutputStream out)
Reads all bytes from this input stream and writes the bytes to the
given output stream in the order that they are read.
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Methods inherited from class java.lang.Object |
public InputStream |
() |
public static InputStream nullInputStream |
() |
While the stream is open, the available(), read(), read(byte[]), read(byte[], int, int), readAllBytes(), readNBytes(byte[], int, int), readNBytes(int), skip(long), skipNBytes(long), and transferTo() methods all behave as if end of stream has been reached. After the stream has been closed, these methods all throw IOException.
The markSupported() method returns false. The mark() method does nothing, and the reset() method throws IOException.
public abstract int read |
() |
throws |
A subclass must provide an implementation of this method.
public int read |
(byte[] b) |
throws |
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.
The read(b) method for class InputStream has the same effect as:
read(b, 0, b.length)
public int read |
(byte[] b, int off, int len) |
throws |
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.
The read(b, off, len) method for class InputStream simply calls the method read() repeatedly. If the first such call results in an IOException, that exception is returned from the call to the read(b, off, len) method. If any subsequent call to read() results in a IOException, the exception is caught and treated as if it were end of 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 blocks until the requested amount of input data len has been read, end of file is detected, or an exception is thrown. Subclasses are encouraged to provide a more efficient implementation of this method.
public byte[] readAllBytes |
() |
throws |
When this stream reaches end of stream, further invocations of this method will return an empty byte array.
Note that this method is intended for simple cases where it is convenient to read all bytes into a byte array. It is not intended for reading input streams with large amounts of data.
The behavior for the case where the input stream is asynchronously closed, or the thread interrupted during the read, is highly input stream specific, and therefore not specified.
If an I/O error occurs reading from the input stream, then it may do so after some, but not all, bytes have been read. Consequently the input stream may not be at end of stream and may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs.
public byte[] readNBytes |
(int len) |
throws |
The length of the returned array equals the number of bytes read from the stream. If len is zero, then no bytes are read and an empty byte array is returned. Otherwise, up to len bytes are read from the stream. Fewer than len bytes may be read if end of stream is encountered.
When this stream reaches end of stream, further invocations of this method will return an empty byte array.
Note that this method is intended for simple cases where it is convenient to read the specified number of bytes into a byte array. The total amount of memory allocated by this method is proportional to the number of bytes read from the stream which is bounded by len. Therefore, the method may be safely called with very large values of len provided sufficient memory is available.
The behavior for the case where the input stream is asynchronously closed, or the thread interrupted during the read, is highly input stream specific, and therefore not specified.
If an I/O error occurs reading from the input stream, then it may do so after some, but not all, bytes have been read. Consequently the input stream may not be at end of stream and may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs.
public int readNBytes |
(byte[] b, int off, int len) |
throws |
In the case where end of stream is reached before len bytes have been read, then the actual number of bytes read will be returned. When this stream reaches end of stream, further invocations of this method will return zero.
If len is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read up to len bytes.
The first byte read is stored into element b[off], the next one in to 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.
The behavior for the case where the input stream is asynchronously closed, or the thread interrupted during the read, is highly input stream specific, and therefore not specified.
If an I/O error occurs reading from the input stream, then it may do so after some, but not all, bytes of b have been updated with data from the input stream. Consequently the input stream and b may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs.
public long skip |
(long n) |
throws |
The skip method implementation of this class creates a byte array and then repeatedly reads into it until n bytes have been read or the end of the stream has been reached. Subclasses are encouraged to provide a more efficient implementation of this method. For instance, the implementation may depend on the ability to seek.
public void skipNBytes |
(long n) |
throws |
This method blocks until the requested number of bytes has been skipped, end of file is reached, or an exception is thrown.
If end of stream is reached before the stream is at the desired position, then an EOFException is thrown.
If an I/O error occurs, then the input stream may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs.
public int available |
() |
throws |
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.
The available method of InputStream always returns 0.
This method should be overridden by subclasses.
public void close |
() |
throws |
The close method of InputStream does nothing.
public void mark |
(int readlimit) |
The readlimit arguments tells this input stream to allow that many bytes to be read before the mark position gets invalidated.
The general contract of mark is that, if the method markSupported returns true, the stream somehow remembers all the bytes read after the call to mark and stands ready to supply those same bytes again if and whenever the method reset is called. However, the stream is not required to remember any data at all if more than readlimit bytes are read from the stream before reset is called.
Marking a closed stream should not have any effect on the stream.
The mark method of InputStream does nothing.
public void reset |
() |
throws |
The general contract of reset is:
The method reset for class InputStream does nothing except throw an IOException.
public boolean markSupported |
() |
public long transferTo |
(OutputStream out) |
throws |
This method may block indefinitely reading from the input stream, or writing to the output stream. The behavior for the case where the input and/or output stream is asynchronously closed, or the thread interrupted during the transfer, is highly input and output stream specific, and therefore not specified.
If an I/O error occurs reading from the input stream or writing to the output stream, then it may do so after some bytes have been read or written. Consequently the input stream may not be at end of stream and one, or both, streams may be in an inconsistent state. It is strongly recommended that both streams be promptly closed if an I/O error occurs.
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FlexDoc/Javadoc 2.0 Demo Java Doc |