Package org.apache.lucene.store

Class IndexInput

java.lang.Object

org.apache.lucene.store.DataInput

org.apache.lucene.store.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 Summary

Constructors

Modifier	Constructor	Description
protected	IndexInput(String resourceDescription)	resourceDescription should be a non-null, opaque string describing this resource; it's returned from toString().

Method Summary

Modifier and Type	Method	Description
IndexInput	clone()	Returns a clone of this stream.
abstract void	close()	Closes the stream to further operations.
abstract long	getFilePointer()	Returns the current position in this file, where the next read will occur.
abstract long	length()	The number of bytes in the file.
abstract void	seek(long pos)	Sets current position in this file, where the next read will occur.
String	toString()

Methods inherited from class org.apache.lucene.store.DataInput

readByte, readBytes, readBytes, readInt, readLong, readShort, readString, readStringSet, readStringStringMap, readVInt, readVLong

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Details

IndexInput

protected IndexInput(String resourceDescription)

resourceDescription should be a non-null, opaque string describing this resource; it's returned from toString().

Method Details

close

public abstract void close()
                    throws IOException

Closes the stream to further operations.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Throws:

IOException

getFilePointer

public abstract long getFilePointer()

Returns the current position in this file, where the next read will occur.

See Also:

• seek(long)

seek

public abstract void seek(long pos)
                   throws IOException

Sets current position in this file, where the next read will occur.

Throws:

IOException

See Also:

• getFilePointer()

length

public abstract long length()

The number of bytes in the file.

toString

public String toString()

Overrides:

toString in class Object

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