Constructor Summary

Method Summary

Constructor Details

• FileInputStream

  public FileInputStream(String name) throwsFileNotFoundException

  Creates aFileInputStream to read from an existing file named by the path namename.Symbolic links are automatically redirected to thetarget of the link. A newFileDescriptor object is created to represent this file connection.

  If the named file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading then aFileNotFoundException is thrown.

  Parameters:

  name - the system-dependent file name.

  Throws:

  FileNotFoundException - if the file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading.

• FileInputStream

  public FileInputStream(File file) throwsFileNotFoundException

  Creates aFileInputStream to read from an existing file represented by theFile objectfile.Symbolic links are automatically redirected to thetarget of the link. A newFileDescriptor object is created to represent this file connection.

  If the named file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading then aFileNotFoundException is thrown.

  Parameters:

  file - the file to be opened for reading.

  Throws:

  FileNotFoundException - if the file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading.

  See Also:

  • File.getPath()

• FileInputStream

  public FileInputStream(FileDescriptor fdObj)

  Creates aFileInputStream by using the file descriptorfdObj, which represents an existing connection to an actual file in the file system.

  IffdObj is null then aNullPointerException is thrown.

  This constructor does not throw an exception iffdObj isinvalid. However, if the methods are invoked on the resulting stream to attempt I/O on the stream, anIOException is thrown.

  Parameters:

  fdObj - the file descriptor to be opened for reading.

Method Details

• read

  public int read() throwsIOException

  Reads a byte of data from this input stream. This method blocks if no input is yet available.

  Specified by:

  read in class InputStream

  Returns:

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

  Throws:

  IOException - if an I/O error occurs.

• read

  public int read(byte[] b) throwsIOException

  Reads up tob.length bytes of data from this input stream into an array of bytes. This method blocks until some input is available.

  Overrides:

  read in class InputStream

  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 file has been reached.

  Throws:

  IOException - if an I/O error occurs.

  See Also:

  • InputStream.read(byte[], int, int)

• read

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

  Reads up tolen bytes of data from this input stream into an array of bytes. Iflen is not zero, the method blocks until some input is available; otherwise, no bytes are read and0 is returned.

  Overrides:

  read in class InputStream

  Parameters:

  b - the buffer into which the data is read.

  off - the start offset in arrayb at which the data is written.

  len - the maximum number of bytes to 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 has been reached.

  Throws:

  NullPointerException - Ifb isnull.

  IndexOutOfBoundsException - Ifoff is negative,len is negative, orlen is greater thanb.length - off

  IOException - if an I/O error occurs.

  See Also:

  • InputStream.read()

• readNBytes

  public byte[] readNBytes(int len) throwsIOException

  Description copied from class: InputStream

  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. Iflen is zero, then no bytes are read and an empty byte array is returned. Otherwise, up tolen bytes are read from the stream. Fewer thanlen 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 bylen. Therefore, the method may be safely called with very large values oflen provided sufficient memory is available.

  The behavior for the case where the input stream isasynchronously 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.

  Overrides:

  readNBytes in class InputStream

  Parameters:

  len - the maximum number of bytes to read

  Returns:

  a byte array containing the bytes read from this input stream

  Throws:

  IOException - if an I/O error occurs

  Since:

  11

• skip

  public long skip(long n) throwsIOException

  Skips over and discardsn bytes of data from the input stream.

  Theskip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly0. Ifn is negative, the method will try to skip backwards. In case the backing file does not support backward skip at its current position, anIOException is thrown. The actual number of bytes skipped is returned. If it skips forwards, it returns a positive value. If it skips backwards, it returns a negative value.

  This method may skip more bytes than what are remaining in the backing file. This produces no exception and the number of bytes skipped may include some number of bytes that were beyond the EOF of the backing file. Attempting to read from the stream after skipping past the end will result in -1 indicating the end of the file.

  Overrides:

  skip in class InputStream

  Parameters:

  n - the number of bytes to be skipped.

  Returns:

  the actual number of bytes skipped.

  Throws:

  IOException - if n is negative, if the stream does not support seek, or if an I/O error occurs.

  See Also:

  • InputStream.skipNBytes(long)

• available

  public int available() throwsIOException

  Returns an estimate of the number of remaining bytes that can be read (or skipped over) from this input stream without blocking by the next invocation of a method for this input stream. Returns 0 when the file position is beyond EOF. The next invocation might be 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.

  In some cases, a non-blocking read (or skip) may appear to be blocked when it is merely slow, for example when reading large files over slow networks.

  Overrides:

  available in class InputStream

  Returns:

  an estimate of the number of remaining bytes that can be read (or skipped over) from this input stream without blocking.

  Throws:

  IOException - if this file input stream has been closed by callingclose or an I/O error occurs.

• close

  public void close() throwsIOException

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

  If this stream has an associated channel then the channel is closed as well.

  Specified by:

  close in interface AutoCloseable

  Specified by:

  close in interface Closeable

  Overrides:

  close in class InputStream

  API Note:

  Overridingclose() to perform cleanup actions is reliable only when called directly or when called by try-with-resources.

  Implementation Requirements:

  Subclasses requiring that resource cleanup take place after a stream becomes unreachable should use theCleaner mechanism.

  If this stream has an associated channel then this method will close the channel, which in turn will close this stream. Subclasses that override this method should be prepared to handle possible reentrant invocation.

  Throws:

  IOException - if an I/O error occurs.

• getFD

  public final FileDescriptor getFD() throwsIOException

  Returns theFileDescriptor object that represents the connection to the actual file in the file system being used by thisFileInputStream.

  Returns:

  the file descriptor object associated with this stream.

  Throws:

  IOException - if an I/O error occurs.

  See Also:

  • FileDescriptor

• getChannel

  public FileChannel getChannel()

  Returns the uniqueFileChannel object associated with this file input stream.

  The initialposition of the returned channel will be equal to the number of bytes read from the file so far. Reading bytes from this stream will increment the channel's position. Changing the channel's position, either explicitly or by reading, will change this stream's file position.

  Returns:

  the file channel associated with this file input stream

  Since:

  1.4