OpenJDK 1.22 · java.io.InputStream · APIdia, the JavaDoc alternative

Modifier and Type	Field and Description
private static final int	DEFAULT_BUFFER_SIZE
private static final int	MAX_BUFFER_SIZE The maximum size of array to allocate.
private static final int	MAX_SKIP_BUFFER_SIZE

Access	Constructor and Description
public	InputStream() Constructor for subclasses to call.

Modifier and Type	Method and Description
public int	Returns: an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking or `0` when it reaches the end of the input stream. 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() Implements java.io.Closeable.close. Closes this input stream and releases any system resources associated with the stream.
public void	mark(int the maximum limit of bytes that can be read before the mark position becomes invalid. readlimit) Marks the current position in this input stream.
public boolean	Returns: `true` if this stream instance supports the mark and reset methods; `false` otherwise. markSupported() Tests if this input stream supports the `mark` and `reset` methods.
public static InputStream	Returns: an `InputStream` which contains no bytes nullInputStream() Returns a new `InputStream` that reads no bytes.
public abstract int	Returns: the next byte of data, or `-1` if the end of the stream is reached. read() Reads the next byte of data from the input stream.
public int	Returns: the total number of bytes read into the buffer, or `-1` if there is no more data because the end of the stream has been reached. read(byte[] the buffer into which the data is read. b) Reads some number of bytes from the input stream and stores them into the buffer array `b`.
public int	Returns: the total number of bytes read into the buffer, or `-1` if there is no more data because the end of the stream has been reached. read(byte[] the buffer into which the data is read. b, int the start offset in array `b` at which the data is written. off, int the maximum number of bytes to read. len) Reads up to `len` bytes of data from the input stream into an array of bytes.
public byte[]	Returns: a byte array containing the bytes read from this input stream readAllBytes() Reads all remaining bytes from the input stream.
public byte[]	Returns: a byte array containing the bytes read from this input stream readNBytes(int the maximum number of bytes to read len) Reads up to a specified number of bytes from the input stream.
public int	Returns: the actual number of bytes read into the buffer readNBytes(byte[] the byte array into which the data is read b, int the start offset in `b` at which the data is written off, int the maximum number of bytes to read len) Reads the requested number of bytes from the input stream into the given byte array.
public void	reset() Repositions this stream to the position at the time the `mark` method was last called on this input stream.
public long	Returns: the actual number of bytes skipped which might be zero. skip(long the number of bytes to be skipped. n) Skips over and discards `n` bytes of data from this input stream.
public void	skipNBytes(long the number of bytes to be skipped. n) Skips over and discards exactly `n` bytes of data from this input stream.
public long	Returns: the number of bytes transferred transferTo(OutputStream the output stream, non-null out) Reads all bytes from this input stream and writes the bytes to the given output stream in the order that they are read.

DEFAULT_BUFFER_SIZE	back to summary
private static final int DEFAULT_BUFFER_SIZE

MAX_BUFFER_SIZE	back to summary
private static final int MAX_BUFFER_SIZE The maximum size of array to allocate. Some VMs reserve some header words in an array. Attempts to allocate larger arrays may result in OutOfMemoryError: Requested array size exceeds VM limit

MAX_SKIP_BUFFER_SIZE	back to summary
private static final int MAX_SKIP_BUFFER_SIZE

InputStream	back to summary
public InputStream() Constructor for subclasses to call.

Method Detail

available back to summary

available	back to summary
public int available() throws IOException 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. Implementation Specification The `available` method of `InputStream` always returns `0`. API Note This method should be overridden by subclasses. Returns:int an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking or `0` when it reaches the end of the input stream. Exceptions IOException: if an I/O error occurs.

public int available() throws IOException

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.

Implementation Specification

The available method of InputStream always returns 0.

API Note

This method should be overridden by subclasses.

Returns:int

an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking or 0 when it reaches the end of the input stream.

Exceptions

IOException:: if an I/O error occurs.

close back to summary

close	back to summary
public void close() throws IOException Implements java.io.Closeable.close. Closes this input stream and releases any system resources associated with the stream. Implementation Specification The `close` method of `InputStream` does nothing. Exceptions IOException: if an I/O error occurs.

public void close() throws IOException

Implements java.io.Closeable.close.

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

Implementation Specification

The close method of InputStream does nothing.

Exceptions

IOException:: if an I/O error occurs.

mark back to summary

mark	back to summary
public void mark(int readlimit) Marks the current position in this input stream. A subsequent call to the `reset` method repositions this stream at the last marked position so that subsequent reads re-read the same bytes. 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. Implementation Specification The `mark` method of `InputStream` does nothing. Parameters readlimit:int the maximum limit of bytes that can be read before the mark position becomes invalid. See Also `java.io.InputStream#reset()`

public void mark(int readlimit)

Marks the current position in this input stream. A subsequent call to the reset method repositions this stream at the last marked position so that subsequent reads re-read the same bytes.

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.

Implementation Specification

The mark method of InputStream does nothing.

Parameters

readlimit:int: the maximum limit of bytes that can be read before the mark position becomes invalid.

See Also

java.io.InputStream#reset()

markSupported back to summary

markSupported	back to summary
public boolean markSupported() Tests if this input stream supports the `mark` and `reset` methods. Whether or not `mark` and `reset` are supported is an invariant property of a particular input stream instance. Implementation Specification The `markSupported` method of `InputStream` returns `false`. Returns:boolean `true` if this stream instance supports the mark and reset methods; `false` otherwise. See Also `java.io.InputStream#mark(int)`, `java.io.InputStream#reset()`

public boolean markSupported()

Tests if this input stream supports the mark and reset methods. Whether or not mark and reset are supported is an invariant property of a particular input stream instance.

Implementation Specification

The markSupported method of InputStream returns false.

Returns:boolean: true if this stream instance supports the mark and reset methods; false otherwise.
See Also: java.io.InputStream#mark(int), java.io.InputStream#reset()

nullInputStream back to summary

nullInputStream	back to summary
public static InputStream nullInputStream() Returns a new `InputStream` that reads no bytes. The returned stream is initially open. The stream is closed by calling the `close()` method. Subsequent calls to `close()` have no effect. 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`. Returns:InputStream an `InputStream` which contains no bytes Since 11

public static InputStream nullInputStream()

Returns a new InputStream that reads no bytes. The returned stream is initially open. The stream is closed by calling the close() method. Subsequent calls to close() have no effect.

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.

Returns:InputStream: an InputStream which contains no bytes
Since: 11

read back to summary

read	back to summary
public abstract int read() throws IOException 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. Returns:int the next byte of data, or `-1` if the end of the stream is reached. Exceptions IOException: if an I/O error occurs.

public abstract int read() throws IOException

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.

Returns:int

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

Exceptions

IOException:: if an I/O error occurs.

read back to summary

read	back to summary
public int read(byte[] b) throws IOException 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. Implementation Specification The `read(b)` method for class `InputStream` has the same effect as: `read(b, 0, b.length)` read(b, 0, b.length) Parameters b:byte[] the buffer into which the data is read. Returns:int the total number of bytes read into the buffer, or `-1` if there is no more data because the end of the stream has been reached. 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. NullPointerException: if `b` is `null`. See Also `java.io.InputStream#read(byte[], int, int)`

public int read(byte[] b) throws IOException

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.

Implementation Specification

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

read(b, 0, b.length)

Parameters

b:byte[]: the buffer into which the data is read.

Returns:int

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

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.
NullPointerException:: if b is null.

read back to summary

read	back to summary
public int read(byte[] b, int off, int len) throws IOException 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. Implementation Specification 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. Parameters b:byte[] the buffer into which the data is read. off:int the start offset in array `b` at which the data is written. len:int the maximum number of bytes to read. Returns:int the total number of bytes read into the buffer, or `-1` if there is no more data because the end of the stream has been reached. 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. NullPointerException: If `b` is `null`. IndexOutOfBoundsException: If `off` is negative, `len` is negative, or `len` is greater than `b.length - off` See Also `java.io.InputStream#read()`

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

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.

Implementation Specification

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.

Parameters

b:byte[]: the buffer into which the data is read.
off:int: the start offset in array b at which the data is written.
len:int: the maximum number of bytes to read.

Returns:int

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

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.
NullPointerException:: If b is null.
IndexOutOfBoundsException:: If off is negative, len is negative, or len is greater than b.length - off

See Also

java.io.InputStream#read()

readAllBytes back to summary

readAllBytes	back to summary
public byte[] readAllBytes() throws IOException Reads all remaining bytes from the input stream. This method blocks until all remaining bytes have been read and end of stream is detected, or an exception is thrown. This method does not close the input stream. 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. Implementation Specification This method invokes `readNBytes(int)` with a length of `Integer#MAX_VALUE`. Returns:byte[] a byte array containing the bytes read from this input stream Exceptions IOException: if an I/O error occurs OutOfMemoryError: if an array of the required size cannot be allocated. Since 9

public byte[] readAllBytes() throws IOException

Reads all remaining bytes from the input stream. This method blocks until all remaining bytes have been read and end of stream is detected, or an exception is thrown. This method does not close the input stream.

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.

Implementation Specification

This method invokes readNBytes(int) with a length of Integer#MAX_VALUE.

Returns:byte[]

a byte array containing the bytes read from this input stream

Exceptions

IOException:: if an I/O error occurs
OutOfMemoryError:: if an array of the required size cannot be allocated.

Since

readNBytes back to summary

readNBytes	back to summary
public byte[] readNBytes(int len) throws IOException Reads up to a specified number of bytes from the input stream. This method blocks until the requested number of bytes has been read, end of stream is detected, or an exception is thrown. This method does not close the input stream. 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. Implementation Note The number of bytes allocated to read data from this stream and return the result is bounded by `2*(long)len`, inclusive. Parameters len:int the maximum number of bytes to read Returns:byte[] a byte array containing the bytes read from this input stream Exceptions IOException: if an I/O error occurs IllegalArgumentException: if `length` is negative OutOfMemoryError: if an array of the required size cannot be allocated. Since 11

public byte[] readNBytes(int len) throws IOException

Reads up to a specified number of bytes from the input stream. This method blocks until the requested number of bytes has been read, end of stream is detected, or an exception is thrown. This method does not close the input stream.

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.

Implementation Note

The number of bytes allocated to read data from this stream and return the result is bounded by 2*(long)len, inclusive.

Parameters

len:int: the maximum number of bytes to read

Returns:byte[]

a byte array containing the bytes read from this input stream

Exceptions

IOException:: if an I/O error occurs
IllegalArgumentException:: if length is negative
OutOfMemoryError:: if an array of the required size cannot be allocated.

Since

readNBytes back to summary

readNBytes	back to summary
public int readNBytes(byte[] b, int off, int len) throws IOException Reads the requested number of bytes from the input stream into the given byte array. This method blocks until `len` bytes of input data have been read, end of stream is detected, or an exception is thrown. The number of bytes actually read, possibly zero, is returned. This method does not close the input stream. 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. Parameters b:byte[] the byte array into which the data is read off:int the start offset in `b` at which the data is written len:int the maximum number of bytes to read Returns:int the actual number of bytes read into the buffer Exceptions IOException: if an I/O error occurs NullPointerException: if `b` is `null` IndexOutOfBoundsException: If `off` is negative, `len` is negative, or `len` is greater than `b.length - off` Since 9

public int readNBytes(byte[] b, int off, int len) throws IOException

Reads the requested number of bytes from the input stream into the given byte array. This method blocks until len bytes of input data have been read, end of stream is detected, or an exception is thrown. The number of bytes actually read, possibly zero, is returned. This method does not close the input stream.

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.

Parameters

b:byte[]: the byte array into which the data is read
off:int: the start offset in b at which the data is written
len:int: the maximum number of bytes to read

Returns:int

the actual number of bytes read into the buffer

Exceptions

IOException:: if an I/O error occurs
NullPointerException:: if b is null
IndexOutOfBoundsException:: If off is negative, len is negative, or len is greater than b.length - off

Since

reset back to summary

reset	back to summary
public void reset() throws IOException Repositions this stream to the position at the time the `mark` method was last called on this input stream. The general contract of `reset` is: If the method `markSupported` returns `true`, then: If the method `mark` has not been called since the stream was created, or the number of bytes read from the stream since `mark` was last called is larger than the argument to `mark` at that last call, then an `IOException` might be thrown. If such an `IOException` is not thrown, then the stream is reset to a state such that all the bytes read since the most recent call to `mark` (or since the start of the file, if `mark` has not been called) will be resupplied to subsequent callers of the `read` method, followed by any bytes that otherwise would have been the next input data as of the time of the call to `reset`. If the method `markSupported` returns `false`, then: The call to `reset` may throw an `IOException`. If an `IOException` is not thrown, then the stream is reset to a fixed state that depends on the particular type of the input stream and how it was created. The bytes that will be supplied to subsequent callers of the `read` method depend on the particular type of the input stream. Implementation Specification The method `reset` for class `InputStream` does nothing except throw an `IOException`. Exceptions IOException: if this stream has not been marked or if the mark has been invalidated. See Also `java.io.InputStream#mark(int)`, `java.io.IOException`

public void reset() throws IOException

Repositions this stream to the position at the time the mark method was last called on this input stream.

The general contract of reset is:

If the method markSupported returns true, then:
- If the method mark has not been called since the stream was created, or the number of bytes read from the stream since mark was last called is larger than the argument to mark at that last call, then an IOException might be thrown.
- If such an IOException is not thrown, then the stream is reset to a state such that all the bytes read since the most recent call to mark (or since the start of the file, if mark has not been called) will be resupplied to subsequent callers of the read method, followed by any bytes that otherwise would have been the next input data as of the time of the call to reset.
If the method markSupported returns false, then:
- The call to reset may throw an IOException.
- If an IOException is not thrown, then the stream is reset to a fixed state that depends on the particular type of the input stream and how it was created. The bytes that will be supplied to subsequent callers of the read method depend on the particular type of the input stream.

Implementation Specification

The method reset for class InputStream does nothing except throw an IOException.

Exceptions

IOException:: if this stream has not been marked or if the mark has been invalidated.

skip back to summary

skip	back to summary
public long skip(long n) throws IOException 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. Implementation Specification 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. Parameters n:long the number of bytes to be skipped. Returns:long the actual number of bytes skipped which might be zero. Exceptions IOException: if an I/O error occurs. See Also `java.io.InputStream#skipNBytes(long)`

public long skip(long n) throws IOException

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.

Implementation Specification

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.

Parameters

n:long: the number of bytes to be skipped.

Returns:long

the actual number of bytes skipped which might be zero.

Exceptions

IOException:: if an I/O error occurs.

See Also

java.io.InputStream#skipNBytes(long)

skipNBytes back to summary

skipNBytes	back to summary
public void skipNBytes(long n) throws IOException Skips over and discards exactly `n` bytes of data from this input stream. If `n` is zero, then no bytes are skipped. If `n` is negative, then no bytes are skipped. Subclasses may handle the negative value differently. 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. Implementation Note Subclasses are encouraged to provide a more efficient implementation of this method. Implementation Specification If `n` is zero or negative, then no bytes are skipped. If `n` is positive, the default implementation of this method invokes `skip()` repeatedly with its parameter equal to the remaining number of bytes to skip until the requested number of bytes has been skipped or an error condition occurs. If at any point the return value of `skip()` is negative or greater than the remaining number of bytes to be skipped, then an `IOException` is thrown. If `skip()` ever returns zero, then `read()` is invoked to read a single byte, and if it returns `-1`, then an `EOFException` is thrown. Any exception thrown by `skip()` or `read()` will be propagated. Parameters n:long the number of bytes to be skipped. Exceptions IOException: if the stream cannot be positioned properly or if an I/O error occurs. EOFException: if end of stream is encountered before the stream can be positioned `n` bytes beyond its position when this method was invoked. Since 12 See Also `java.io.InputStream#skip(long)`

public void skipNBytes(long n) throws IOException

Skips over and discards exactly n bytes of data from this input stream. If n is zero, then no bytes are skipped. If n is negative, then no bytes are skipped. Subclasses may handle the negative value differently.

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.

Implementation Note

Subclasses are encouraged to provide a more efficient implementation of this method.

Implementation Specification

If n is zero or negative, then no bytes are skipped. If n is positive, the default implementation of this method invokes skip() repeatedly with its parameter equal to the remaining number of bytes to skip until the requested number of bytes has been skipped or an error condition occurs. If at any point the return value of skip() is negative or greater than the remaining number of bytes to be skipped, then an IOException is thrown. If skip() ever returns zero, then read() is invoked to read a single byte, and if it returns -1, then an EOFException is thrown. Any exception thrown by skip() or read() will be propagated.

Parameters

n:long: the number of bytes to be skipped.

Exceptions

IOException:: if the stream cannot be positioned properly or if an I/O error occurs.
EOFException:: if end of stream is encountered before the stream can be positioned n bytes beyond its position when this method was invoked.

Since

See Also

java.io.InputStream#skip(long)

transferTo back to summary

transferTo	back to summary
public long transferTo(OutputStream out) throws IOException Reads all bytes from this input stream and writes the bytes to the given output stream in the order that they are read. On return, this input stream will be at end of stream. This method does not close either stream. 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 the total number of bytes transferred is greater than Long#MAX_VALUE, then `Long.MAX_VALUE` will be returned. 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. Parameters out:OutputStream the output stream, non-null Returns:long the number of bytes transferred Exceptions IOException: if an I/O error occurs when reading or writing NullPointerException: if `out` is `null` Since 9

public long transferTo(OutputStream out) throws IOException

Reads all bytes from this input stream and writes the bytes to the given output stream in the order that they are read. On return, this input stream will be at end of stream. This method does not close either stream.

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 the total number of bytes transferred is greater than Long#MAX_VALUE, then Long.MAX_VALUE will be returned.

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.

Parameters

out:OutputStream: the output stream, non-null

Returns:long

the number of bytes transferred

Exceptions

IOException:: if an I/O error occurs when reading or writing
NullPointerException:: if out is null

Since

public abstract Class InputStream

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