content: package org.apache.lucene.store;
  
  /**
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  import java.io.IOException;
  import java.io.Closeable;
  
  /** Abstract base class for output to a file in a Directory.  A random-access
   * output stream.  Used for all Lucene index output operations.
   * @see Directory
   * @see IndexInput
   */
  public abstract class IndexOutput extends DataOutput implements Closeable {
  
    /** Forces any buffered output to be written. */
    public abstract void flush() throws IOException;
  
    /** Closes this stream to further operations. */
    public abstract void close() throws IOException;
  
    /** Returns the current position in this file, where the next write will
     * occur.
     * @see #seek(long)
     */
    public abstract long getFilePointer();
  
    /** Sets current position in this file, where the next write will occur.
     * @see #getFilePointer()
     */
    public abstract void seek(long pos) throws IOException;
  
    /** The number of bytes in the file. */
    public abstract long length() throws IOException;
  
    /** Set the file length. By default, this method does
     * nothing (it's optional for a Directory to implement
     * it).  But, certain Directory implementations (for
     * example @see FSDirectory) can use this to inform the
     * underlying IO system to pre-allocate the file to the
     * specified size.  If the length is longer than the
     * current file length, the bytes added to the file are
     * undefined.  Otherwise the file is truncated.
     * @param length file length
     */
    public void setLength(long length) throws IOException {}
  }
  