vector/src/main/java/org/apache/arrow/vector/BaseLargeVariableWidthVector.java [847:986]:
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          target.validityBuffer.setByte(i, (b1 + b2));
        }
        /* Copying the last piece is done in the following manner:
         * if the source vector has 1 or more bytes remaining, we copy
         * the last piece as a byte formed by shifting data
         * from the current byte and the next byte.
         *
         * if the source vector has no more bytes remaining
         * (we are at the last byte), we copy the last piece as a byte
         * by shifting data from the current byte.
         */
        if ((firstByteSource + byteSizeTarget - 1) < lastByteSource) {
          byte b1 =
              BitVectorHelper.getBitsFromCurrentByte(
                  this.validityBuffer, firstByteSource + byteSizeTarget - 1, offset);
          byte b2 =
              BitVectorHelper.getBitsFromNextByte(
                  this.validityBuffer, firstByteSource + byteSizeTarget, offset);

          target.validityBuffer.setByte(byteSizeTarget - 1, b1 + b2);
        } else {
          byte b1 =
              BitVectorHelper.getBitsFromCurrentByte(
                  this.validityBuffer, firstByteSource + byteSizeTarget - 1, offset);
          target.validityBuffer.setByte(byteSizeTarget - 1, b1);
        }
      }
    }
  }

  /*----------------------------------------------------------------*
  |                                                                |
  |                common getters and setters                      |
  |                                                                |
  *----------------------------------------------------------------*/

  /**
   * Get the number of elements that are null in the vector.
   *
   * @return the number of null elements.
   */
  @Override
  public int getNullCount() {
    return BitVectorHelper.getNullCount(validityBuffer, valueCount);
  }

  /**
   * Check if the given index is within the current value capacity of the vector.
   *
   * @param index position to check
   * @return true if index is within the current value capacity
   */
  public boolean isSafe(int index) {
    return index < getValueCapacity();
  }

  /**
   * Check if element at given index is null.
   *
   * @param index position of element
   * @return true if element at given index is null
   */
  @Override
  public boolean isNull(int index) {
    return (isSet(index) == 0);
  }

  /**
   * Same as {@link #isNull(int)}.
   *
   * @param index position of element
   * @return 1 if element at given index is not null, 0 otherwise
   */
  public int isSet(int index) {
    final int byteIndex = index >> 3;
    final byte b = validityBuffer.getByte(byteIndex);
    final int bitIndex = index & 7;
    return (b >> bitIndex) & 0x01;
  }

  /**
   * Get the value count of vector. This will always be zero unless setValueCount(int) has been
   * called prior to calling this.
   *
   * @return valueCount for the vector
   */
  @Override
  public int getValueCount() {
    return valueCount;
  }

  /**
   * Sets the value count for the vector.
   *
   * @param valueCount value count
   */
  @Override
  public void setValueCount(int valueCount) {
    assert valueCount >= 0;
    this.valueCount = valueCount;
    while (valueCount > getValueCapacity()) {
      reallocValidityAndOffsetBuffers();
    }
    fillHoles(valueCount);
    lastSet = valueCount - 1;
    setReaderAndWriterIndex();
  }

  /**
   * Create holes in the vector upto the given index (exclusive). Holes will be created from the
   * current last set position in the vector.
   *
   * @param index target index
   */
  @Override
  public void fillEmpties(int index) {
    handleSafe(index, emptyByteArray.length);
    fillHoles(index);
    lastSet = index - 1;
  }

  /**
   * Set the index of last non-null element in the vector. It is important to call this method with
   * appropriate value before calling {@link #setValueCount(int)}.
   *
   * @param value desired index of last non-null element.
   */
  @Override
  public void setLastSet(int value) {
    lastSet = value;
  }

  /**
   * Get the index of last non-null element in the vector.
   *
   * @return index of the last non-null element
   */
  @Override
  public int getLastSet() {
    return lastSet;
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vector/src/main/java/org/apache/arrow/vector/BaseVariableWidthVector.java [897:1034]:
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      target.validityBuffer.setByte(i, (b1 + b2));
    }
    /* Copying the last piece is done in the following manner:
     * if the source vector has 1 or more bytes remaining, we copy
     * the last piece as a byte formed by shifting data
     * from the current byte and the next byte.
     *
     * if the source vector has no more bytes remaining
     * (we are at the last byte), we copy the last piece as a byte
     * by shifting data from the current byte.
     */
    if ((firstByteSource + byteSizeTarget - 1) < lastByteSource) {
      byte b1 =
          BitVectorHelper.getBitsFromCurrentByte(
              this.validityBuffer, firstByteSource + byteSizeTarget - 1, offset);
      byte b2 =
          BitVectorHelper.getBitsFromNextByte(
              this.validityBuffer, firstByteSource + byteSizeTarget, offset);

      target.validityBuffer.setByte(byteSizeTarget - 1, b1 + b2);
    } else {
      byte b1 =
          BitVectorHelper.getBitsFromCurrentByte(
              this.validityBuffer, firstByteSource + byteSizeTarget - 1, offset);
      target.validityBuffer.setByte(byteSizeTarget - 1, b1);
    }
  }

  /*----------------------------------------------------------------*
  |                                                                |
  |                common getters and setters                      |
  |                                                                |
  *----------------------------------------------------------------*/

  /**
   * Get the number of elements that are null in the vector.
   *
   * @return the number of null elements.
   */
  @Override
  public int getNullCount() {
    return BitVectorHelper.getNullCount(validityBuffer, valueCount);
  }

  /**
   * Check if the given index is within the current value capacity of the vector.
   *
   * @param index position to check
   * @return true if index is within the current value capacity
   */
  public boolean isSafe(int index) {
    return index < getValueCapacity();
  }

  /**
   * Check if element at given index is null.
   *
   * @param index position of element
   * @return true if element at given index is null
   */
  @Override
  public boolean isNull(int index) {
    return (isSet(index) == 0);
  }

  /**
   * Same as {@link #isNull(int)}.
   *
   * @param index position of element
   * @return 1 if element at given index is not null, 0 otherwise
   */
  public int isSet(int index) {
    final int byteIndex = index >> 3;
    final byte b = validityBuffer.getByte(byteIndex);
    final int bitIndex = index & 7;
    return (b >> bitIndex) & 0x01;
  }

  /**
   * Get the value count of vector. This will always be zero unless setValueCount(int) has been
   * called prior to calling this.
   *
   * @return valueCount for the vector
   */
  @Override
  public int getValueCount() {
    return valueCount;
  }

  /**
   * Sets the value count for the vector.
   *
   * @param valueCount value count
   */
  @Override
  public void setValueCount(int valueCount) {
    assert valueCount >= 0;
    this.valueCount = valueCount;
    while (valueCount > getValueCapacity()) {
      reallocValidityAndOffsetBuffers();
    }
    fillHoles(valueCount);
    lastSet = valueCount - 1;
    setReaderAndWriterIndex();
  }

  /**
   * Create holes in the vector upto the given index (exclusive). Holes will be created from the
   * current last set position in the vector.
   *
   * @param index target index
   */
  @Override
  public void fillEmpties(int index) {
    handleSafe(index, emptyByteArray.length);
    fillHoles(index);
    lastSet = index - 1;
  }

  /**
   * Set the index of last non-null element in the vector. It is important to call this method with
   * appropriate value before calling {@link #setValueCount(int)}.
   *
   * @param value desired index of last non-null element.
   */
  @Override
  public void setLastSet(int value) {
    lastSet = value;
  }

  /**
   * Get the index of last non-null element in the vector.
   *
   * @return index of the last non-null element
   */
  @Override
  public int getLastSet() {
    return lastSet;
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