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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 2002, 2015 Oracle and/or its affiliates. All rights reserved.
*
*/
package com.sleepycat.persist;
import java.io.Closeable;
import java.util.Iterator;
import com.sleepycat.db.DatabaseException;
import com.sleepycat.db.LockMode;
/**
* Cursor operations limited to traversing forward. See {@link EntityCursor}
* for general information on cursors.
*
* <p>{@code ForwardCursor} objects are <em>not</em> thread-safe. Cursors
* should be opened, used and closed by a single thread.</p>
*
* <p><em>WARNING:</em> Cursors must always be closed to prevent resource leaks
* which could lead to the index becoming unusable or cause an
* <code>OutOfMemoryError</code>. To ensure that a cursor is closed in the
* face of exceptions, close it in a finally block.</p>
*
* @author Mark Hayes
*/
public interface ForwardCursor<V> extends Iterable<V>
{
/**
* Moves the cursor to the next value and returns it, or returns null
* if there are no more values in the cursor range. If the cursor is
* uninitialized, this method returns the first value.
*
* <p>{@link LockMode#DEFAULT} is used implicitly.</p>
*
* @return the next value, or null if there are no more values in the
* cursor range.
*
*
* @throws DatabaseException the base class for all BDB exceptions.
*/
V next()
throws DatabaseException;
/**
* Moves the cursor to the next value and returns it, or returns null
* if there are no more values in the cursor range. If the cursor is
* uninitialized, this method returns the first value.
*
* @param lockMode the lock mode to use for this operation, or null to
* use {@link LockMode#DEFAULT}.
*
* @return the next value, or null if there are no more values in the
* cursor range.
*
*
* @throws DatabaseException the base class for all BDB exceptions.
*/
V next(LockMode lockMode)
throws DatabaseException;
/**
* Returns an iterator over the key range, starting with the value
* following the current position or at the first value if the cursor is
* uninitialized.
*
* <p>{@link LockMode#DEFAULT} is used implicitly.</p>
*
* @return the iterator.
*/
Iterator<V> iterator();
/**
* Returns an iterator over the key range, starting with the value
* following the current position or at the first value if the cursor is
* uninitialized.
*
* @param lockMode the lock mode to use for all operations performed
* using the iterator, or null to use {@link LockMode#DEFAULT}.
*
* @return the iterator.
*/
Iterator<V> iterator(LockMode lockMode);
/**
* Closes the cursor.
*
* @throws DatabaseException the base class for all BDB exceptions.
*/
void close()
throws DatabaseException;
}
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