Class IndexInput

  • All Implemented Interfaces:
    Closeable, AutoCloseable, Cloneable
    Direct Known Subclasses:
    BufferedIndexInput, ChecksumIndexInput, RAMInputStream

    public abstract class IndexInput
    extends DataInput
    implements Cloneable, Closeable
    Abstract base class for input from a file in a Directory. A random-access input stream. Used for all Lucene index input operations.

    IndexInput may only be used from one thread, because it is not thread safe (it keeps internal state like file position). To allow multithreaded use, every IndexInput instance must be cloned before used in another thread. Subclasses must therefore implement clone(), returning a new IndexInput which operates on the same underlying resource, but positioned independently. Lucene never closes cloned IndexInputs, it will only do this on the original one. The original instance must take care that cloned instances throw AlreadyClosedException when the original one is closed.

    See Also:
    Directory
    • Constructor Detail

      • IndexInput

        protected IndexInput​(String resourceDescription)
        resourceDescription should be a non-null, opaque string describing this resource; it's returned from toString().
    • Method Detail

      • getFilePointer

        public abstract long getFilePointer()
        Returns the current position in this file, where the next read will occur.
        See Also:
        seek(long)
      • length

        public abstract long length()
        The number of bytes in the file.
      • clone

        public IndexInput clone()
        Returns a clone of this stream.

        Clones of a stream access the same data, and are positioned at the same point as the stream they were cloned from.

        Expert: Subclasses must ensure that clones may be positioned at different points in the input from each other and from the stream they were cloned from.

        Warning: Lucene never closes cloned IndexInputs, it will only do this on the original one. The original instance must take care that cloned instances throw AlreadyClosedException when the original one is closed.

        Overrides:
        clone in class DataInput