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Lucene example source code file (IndexInput.java)

This example Lucene source code file (IndexInput.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

cloneable,closeable, cloneable,closeable, datainput, deprecated, deprecated, indexinput, indexinput, io, ioexception, ioexception

The Lucene IndexInput.java source code

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,
 * 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 input from a file in a {@link Directory}.  A
 * random-access input stream.  Used for all Lucene index input operations.
 * @see Directory
public abstract class IndexInput extends DataInput implements Cloneable,Closeable {

  protected byte[] copyBuf = null;

   * Expert
   * Similar to {@link #readChars(char[], int, int)} but does not do any conversion operations on the bytes it is reading in.  It still
   * has to invoke {@link #readByte()} just as {@link #readChars(char[], int, int)} does, but it does not need a buffer to store anything
   * and it does not have to do any of the bitwise operations, since we don't actually care what is in the byte except to determine
   * how many more bytes to read
   * @param length The number of chars to read
   * @deprecated this method operates on old "modified utf8" encoded
   *             strings
  public void skipChars(int length) throws IOException{
    for (int i = 0; i < length; i++) {
      byte b = readByte();
      if ((b & 0x80) == 0){
        //do nothing, we only need one byte
      } else if ((b & 0xE0) != 0xE0) {
        readByte();//read an additional byte
      } else {      
        //read two additional bytes.

  /** Closes the stream to further operations. */
  public abstract void close() throws IOException;

  /** Returns the current position in this file, where the next read will
   * occur.
   * @see #seek(long)
  public abstract long getFilePointer();

  /** Sets current position in this file, where the next read will occur.
   * @see #getFilePointer()
  public abstract void seek(long pos) throws IOException;

  /** The number of bytes in the file. */
  public abstract long length();

   * Copies <code>numBytes bytes to the given {@link IndexOutput}.
   * <p>
   * <b>NOTE: this method uses an intermediate buffer to copy the bytes.
   * Consider overriding it in your implementation, if you can make a better,
   * optimized copy.
   * <p>
   * <b>NOTE ensure that there are enough bytes in the input to copy to
   * output. Otherwise, different exceptions may be thrown, depending on the
   * implementation.
  public void copyBytes(IndexOutput out, long numBytes) throws IOException {
    assert numBytes >= 0: "numBytes=" + numBytes;

    if (copyBuf == null) {
      copyBuf = new byte[BufferedIndexInput.BUFFER_SIZE];

    while (numBytes > 0) {
      final int toCopy = (int) (numBytes > copyBuf.length ? copyBuf.length : numBytes);
      readBytes(copyBuf, 0, toCopy);
      out.writeBytes(copyBuf, 0, toCopy);
      numBytes -= toCopy;

Other Lucene examples (source code examples)

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