Interface BasicInput

All Known Implementing Classes:
BlockInput, BlockMappedInput, BufferedRandomInput, ByteBufferInput, MultiByteBufferInput, SimpleMappedInput

public interface BasicInput
Interface defining the basic data input operations required for the FITS reading classes. All the read operations operate at the current position of the assumed stream and advance the current position past the item they just read. Storage is FITS-like, which, happily, matches ByteBuffer conventions. Random access may or may not be supported.

This interface has some similarities to DataInput, and that interface could have been used instead, but this one is explicitly used for the hand-coded FITS reader implementation to make clear which operations need to be efficient. At present no multi-byte (or multi-other-primitive-type) read operations are included, since it's not clear that these are required in practice for efficient table input, though for (uncommon?) tables that have columns with large array values that might not be true. If that turns out to be an important use case, such methods can be added to this interface, implemented in its implementations, and used in the clients of this interface.

Instances of this are not expected to be safe for use from multiple threads. Depending on the implementation, ignoring that fact may be a very bad idea indeed.

Since:
1 Dec 2014
Author:
Mark Taylor
  • Method Summary

    Modifier and Type
    Method
    Description
    void
    Releases resources belonging to this object.
    long
    Returns the curent position in this stream (optional operation).
    boolean
    Indicates whether this object supports random access.
    byte
    Reads a byte from the stream.
    void
    readBytes(byte[] buf)
    Reads bytes into an array from the stream.
    double
    Reads an 8-byte floating point value from the stream.
    float
    Reads a 4-byte floating point value from the stream.
    int
    Reads a 4-byte integer from the stream.
    long
    Reads an 8-byte integer from the stream.
    short
    Reads a 2-byte integer from the stream.
    void
    seek(long offset)
    Moves the current position of this stream to a given byte offset (optional operation).
    void
    skip(long nbyte)
    Skips a given number of bytes forwards through the stream.
  • Method Details

    • readByte

      byte readByte() throws IOException
      Reads a byte from the stream. The current position is advanced.
      Returns:
      byte value
      Throws:
      IOException
    • readShort

      short readShort() throws IOException
      Reads a 2-byte integer from the stream. The current position is advanced.
      Returns:
      short value
      Throws:
      IOException
    • readInt

      int readInt() throws IOException
      Reads a 4-byte integer from the stream. The current position is advanced.
      Returns:
      int value
      Throws:
      IOException
    • readLong

      long readLong() throws IOException
      Reads an 8-byte integer from the stream. The current position is advanced.
      Returns:
      long value
      Throws:
      IOException
    • readFloat

      float readFloat() throws IOException
      Reads a 4-byte floating point value from the stream. The current position is advanced.
      Returns:
      float value
      Throws:
      IOException
    • readDouble

      double readDouble() throws IOException
      Reads an 8-byte floating point value from the stream. The current position is advanced.
      Returns:
      double value
      Throws:
      IOException
    • readBytes

      void readBytes(byte[] buf) throws IOException
      Reads bytes into an array from the stream. The current position is advanced.
      Parameters:
      buf - array into which the bytes are read; the number of bytes read is the length of the array
      Throws:
      IOException
    • skip

      void skip(long nbyte) throws IOException
      Skips a given number of bytes forwards through the stream. An exception is thrown if there are not enough bytes left.
      Parameters:
      nbyte - number of bytes to skip
      Throws:
      IOException
    • close

      void close() throws IOException
      Releases resources belonging to this object. Attempts to use it after a call to this method result in undefined behaviour.
      Throws:
      IOException
    • isRandom

      boolean isRandom()
      Indicates whether this object supports random access. The seek and getOffset methods may only be called if this method returns true.
      Returns:
      true iff random access is supported
    • seek

      void seek(long offset) throws IOException
      Moves the current position of this stream to a given byte offset (optional operation).
      Throws:
      UnsupportedOperationException - if not random-access
      IOException
    • getOffset

      long getOffset()
      Returns the curent position in this stream (optional operation).
      Throws:
      UnsupportedOperationException - if not random-access