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Lucene example source code file (ArrayUtil.java)

This example Lucene source code file (ArrayUtil.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

arrayutil, comparable, comparator, comparator, deprecated, illegalargumentexception, numberformatexception, numberformatexception, override, override, sortertemplate, t, t, unable, util

The Lucene ArrayUtil.java source code

package org.apache.lucene.util;

/**
 * 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.util.Collection;
import java.util.Comparator;

/**
 * Methods for manipulating arrays.
 *
 * @lucene.internal
 */
public final class ArrayUtil {

  /**
   * @deprecated This constructor was not intended to be public and should not be used.
   *  This class contains solely a static utility methods.
   *  It will be made private in Lucene 4.0
   */
  // make private in 4.0!
  @Deprecated
  public ArrayUtil() {} // no instance

  /*
     Begin Apache Harmony code

     Revision taken on Friday, June 12. https://svn.apache.org/repos/asf/harmony/enhanced/classlib/archive/java6/modules/luni/src/main/java/java/lang/Integer.java

   */

  /**
   * Parses the string argument as if it was an int value and returns the
   * result. Throws NumberFormatException if the string does not represent an
   * int quantity.
   *
   * @param chars a string representation of an int quantity.
   * @return int the value represented by the argument
   * @throws NumberFormatException if the argument could not be parsed as an int quantity.
   */
  public static int parseInt(char[] chars) throws NumberFormatException {
    return parseInt(chars, 0, chars.length, 10);
  }

  /**
   * Parses a char array into an int.
   * @param chars the character array
   * @param offset The offset into the array
   * @param len The length
   * @return the int
   * @throws NumberFormatException if it can't parse
   */
  public static int parseInt(char[] chars, int offset, int len) throws NumberFormatException {
    return parseInt(chars, offset, len, 10);
  }

  /**
   * Parses the string argument as if it was an int value and returns the
   * result. Throws NumberFormatException if the string does not represent an
   * int quantity. The second argument specifies the radix to use when parsing
   * the value.
   *
   * @param chars a string representation of an int quantity.
   * @param radix the base to use for conversion.
   * @return int the value represented by the argument
   * @throws NumberFormatException if the argument could not be parsed as an int quantity.
   */
  public static int parseInt(char[] chars, int offset, int len, int radix)
          throws NumberFormatException {
    if (chars == null || radix < Character.MIN_RADIX
            || radix > Character.MAX_RADIX) {
      throw new NumberFormatException();
    }
    int  i = 0;
    if (len == 0) {
      throw new NumberFormatException("chars length is 0");
    }
    boolean negative = chars[offset + i] == '-';
    if (negative && ++i == len) {
      throw new NumberFormatException("can't convert to an int");
    }
    if (negative == true){
      offset++;
      len--;
    }
    return parse(chars, offset, len, radix, negative);
  }


  private static int parse(char[] chars, int offset, int len, int radix,
                           boolean negative) throws NumberFormatException {
    int max = Integer.MIN_VALUE / radix;
    int result = 0;
    for (int i = 0; i < len; i++){
      int digit = Character.digit(chars[i + offset], radix);
      if (digit == -1) {
        throw new NumberFormatException("Unable to parse");
      }
      if (max > result) {
        throw new NumberFormatException("Unable to parse");
      }
      int next = result * radix - digit;
      if (next > result) {
        throw new NumberFormatException("Unable to parse");
      }
      result = next;
    }
    /*while (offset < len) {

    }*/
    if (!negative) {
      result = -result;
      if (result < 0) {
        throw new NumberFormatException("Unable to parse");
      }
    }
    return result;
  }


  /*

 END APACHE HARMONY CODE
  */

  /** Returns an array size >= minTargetSize, generally
   *  over-allocating exponentially to achieve amortized
   *  linear-time cost as the array grows.
   *
   *  NOTE: this was originally borrowed from Python 2.4.2
   *  listobject.c sources (attribution in LICENSE.txt), but
   *  has now been substantially changed based on
   *  discussions from java-dev thread with subject "Dynamic
   *  array reallocation algorithms", started on Jan 12
   *  2010.
   *
   * @param minTargetSize Minimum required value to be returned.
   * @param bytesPerElement Bytes used by each element of
   * the array.  See constants in {@link RamUsageEstimator}.
   *
   * @lucene.internal
   */

  public static int oversize(int minTargetSize, int bytesPerElement) {

    if (minTargetSize < 0) {
      // catch usage that accidentally overflows int
      throw new IllegalArgumentException("invalid array size " + minTargetSize);
    }

    if (minTargetSize == 0) {
      // wait until at least one element is requested
      return 0;
    }

    // asymptotic exponential growth by 1/8th, favors
    // spending a bit more CPU to not tie up too much wasted
    // RAM:
    int extra = minTargetSize >> 3;

    if (extra < 3) {
      // for very small arrays, where constant overhead of
      // realloc is presumably relatively high, we grow
      // faster
      extra = 3;
    }

    int newSize = minTargetSize + extra;

    // add 7 to allow for worst case byte alignment addition below:
    if (newSize+7 < 0) {
      // int overflowed -- return max allowed array size
      return Integer.MAX_VALUE;
    }

    if (Constants.JRE_IS_64BIT) {
      // round up to 8 byte alignment in 64bit env
      switch(bytesPerElement) {
      case 4:
        // round up to multiple of 2
        return (newSize + 1) & 0x7ffffffe;
      case 2:
        // round up to multiple of 4
        return (newSize + 3) & 0x7ffffffc;
      case 1:
        // round up to multiple of 8
        return (newSize + 7) & 0x7ffffff8;
      case 8:
        // no rounding
      default:
        // odd (invalid?) size
        return newSize;
      }
    } else {
      // round up to 4 byte alignment in 64bit env
      switch(bytesPerElement) {
      case 2:
        // round up to multiple of 2
        return (newSize + 1) & 0x7ffffffe;
      case 1:
        // round up to multiple of 4
        return (newSize + 3) & 0x7ffffffc;
      case 4:
      case 8:
        // no rounding
      default:
        // odd (invalid?) size
        return newSize;
      }
    }
  }

  public static int getShrinkSize(int currentSize, int targetSize, int bytesPerElement) {
    final int newSize = oversize(targetSize, bytesPerElement);
    // Only reallocate if we are "substantially" smaller.
    // This saves us from "running hot" (constantly making a
    // bit bigger then a bit smaller, over and over):
    if (newSize < currentSize / 2)
      return newSize;
    else
      return currentSize;
  }

  public static short[] grow(short[] array, int minSize) {
    if (array.length < minSize) {
      short[] newArray = new short[oversize(minSize, RamUsageEstimator.NUM_BYTES_SHORT)];
      System.arraycopy(array, 0, newArray, 0, array.length);
      return newArray;
    } else
      return array;
  }

  public static short[] grow(short[] array) {
    return grow(array, 1 + array.length);
  }
  
  public static float[] grow(float[] array, int minSize) {
    if (array.length < minSize) {
      float[] newArray = new float[oversize(minSize, RamUsageEstimator.NUM_BYTES_FLOAT)];
      System.arraycopy(array, 0, newArray, 0, array.length);
      return newArray;
    } else
      return array;
  }

  public static float[] grow(float[] array) {
    return grow(array, 1 + array.length);
  }

  public static short[] shrink(short[] array, int targetSize) {
    final int newSize = getShrinkSize(array.length, targetSize, RamUsageEstimator.NUM_BYTES_SHORT);
    if (newSize != array.length) {
      short[] newArray = new short[newSize];
      System.arraycopy(array, 0, newArray, 0, newSize);
      return newArray;
    } else
      return array;
  }

  public static int[] grow(int[] array, int minSize) {
    if (array.length < minSize) {
      int[] newArray = new int[oversize(minSize, RamUsageEstimator.NUM_BYTES_INT)];
      System.arraycopy(array, 0, newArray, 0, array.length);
      return newArray;
    } else
      return array;
  }

  public static int[] grow(int[] array) {
    return grow(array, 1 + array.length);
  }

  public static int[] shrink(int[] array, int targetSize) {
    final int newSize = getShrinkSize(array.length, targetSize, RamUsageEstimator.NUM_BYTES_INT);
    if (newSize != array.length) {
      int[] newArray = new int[newSize];
      System.arraycopy(array, 0, newArray, 0, newSize);
      return newArray;
    } else
      return array;
  }

  public static long[] grow(long[] array, int minSize) {
    if (array.length < minSize) {
      long[] newArray = new long[oversize(minSize, RamUsageEstimator.NUM_BYTES_LONG)];
      System.arraycopy(array, 0, newArray, 0, array.length);
      return newArray;
    } else
      return array;
  }

  public static long[] grow(long[] array) {
    return grow(array, 1 + array.length);
  }

  public static long[] shrink(long[] array, int targetSize) {
    final int newSize = getShrinkSize(array.length, targetSize, RamUsageEstimator.NUM_BYTES_LONG);
    if (newSize != array.length) {
      long[] newArray = new long[newSize];
      System.arraycopy(array, 0, newArray, 0, newSize);
      return newArray;
    } else
      return array;
  }

  public static byte[] grow(byte[] array, int minSize) {
    if (array.length < minSize) {
      byte[] newArray = new byte[oversize(minSize, 1)];
      System.arraycopy(array, 0, newArray, 0, array.length);
      return newArray;
    } else
      return array;
  }

  public static byte[] grow(byte[] array) {
    return grow(array, 1 + array.length);
  }

  public static byte[] shrink(byte[] array, int targetSize) {
    final int newSize = getShrinkSize(array.length, targetSize, 1);
    if (newSize != array.length) {
      byte[] newArray = new byte[newSize];
      System.arraycopy(array, 0, newArray, 0, newSize);
      return newArray;
    } else
      return array;
  }

  public static boolean[] grow(boolean[] array, int minSize) {
    if (array.length < minSize) {
      boolean[] newArray = new boolean[oversize(minSize, 1)];
      System.arraycopy(array, 0, newArray, 0, array.length);
      return newArray;
    } else
      return array;
  }

  public static boolean[] grow(boolean[] array) {
    return grow(array, 1 + array.length);
  }

  public static boolean[] shrink(boolean[] array, int targetSize) {
    final int newSize = getShrinkSize(array.length, targetSize, 1);
    if (newSize != array.length) {
      boolean[] newArray = new boolean[newSize];
      System.arraycopy(array, 0, newArray, 0, newSize);
      return newArray;
    } else
      return array;
  }

  public static char[] grow(char[] array, int minSize) {
    if (array.length < minSize) {
      char[] newArray = new char[oversize(minSize, RamUsageEstimator.NUM_BYTES_CHAR)];
      System.arraycopy(array, 0, newArray, 0, array.length);
      return newArray;
    } else
      return array;
  }

  public static char[] grow(char[] array) {
    return grow(array, 1 + array.length);
  }

  public static char[] shrink(char[] array, int targetSize) {
    final int newSize = getShrinkSize(array.length, targetSize, RamUsageEstimator.NUM_BYTES_CHAR);
    if (newSize != array.length) {
      char[] newArray = new char[newSize];
      System.arraycopy(array, 0, newArray, 0, newSize);
      return newArray;
    } else
      return array;
  }

  /**
   * Returns hash of chars in range start (inclusive) to
   * end (inclusive)
   */
  public static int hashCode(char[] array, int start, int end) {
    int code = 0;
    for (int i = end - 1; i >= start; i--)
      code = code * 31 + array[i];
    return code;
  }

  /**
   * Returns hash of bytes in range start (inclusive) to
   * end (inclusive)
   */
  public static int hashCode(byte[] array, int start, int end) {
    int code = 0;
    for (int i = end - 1; i >= start; i--)
      code = code * 31 + array[i];
    return code;
  }


  // Since Arrays.equals doesn't implement offsets for equals
  /**
   * See if two array slices are the same.
   *
   * @param left        The left array to compare
   * @param offsetLeft  The offset into the array.  Must be positive
   * @param right       The right array to compare
   * @param offsetRight the offset into the right array.  Must be positive
   * @param length      The length of the section of the array to compare
   * @return true if the two arrays, starting at their respective offsets, are equal
   * 
   * @see java.util.Arrays#equals(char[], char[])
   */
  public static boolean equals(char[] left, int offsetLeft, char[] right, int offsetRight, int length) {
    if ((offsetLeft + length <= left.length) && (offsetRight + length <= right.length)) {
      for (int i = 0; i < length; i++) {
        if (left[offsetLeft + i] != right[offsetRight + i]) {
          return false;
        }

      }
      return true;
    }
    return false;
  }

  // Since Arrays.equals doesn't implement offsets for equals
  /**
   * See if two array slices are the same.
   *
   * @param left        The left array to compare
   * @param offsetLeft  The offset into the array.  Must be positive
   * @param right       The right array to compare
   * @param offsetRight the offset into the right array.  Must be positive
   * @param length      The length of the section of the array to compare
   * @return true if the two arrays, starting at their respective offsets, are equal
   * 
   * @see java.util.Arrays#equals(char[], char[])
   */
  public static boolean equals(int[] left, int offsetLeft, int[] right, int offsetRight, int length) {
    if ((offsetLeft + length <= left.length) && (offsetRight + length <= right.length)) {
      for (int i = 0; i < length; i++) {
        if (left[offsetLeft + i] != right[offsetRight + i]) {
          return false;
        }

      }
      return true;
    }
    return false;
  }

  public static int[] toIntArray(Collection<Integer> ints) {

    final int[] result = new int[ints.size()];
    int upto = 0;
    for(int v : ints) {
      result[upto++] = v;
    }

    // paranoia:
    assert upto == result.length;

    return result;
  }
  
  /** SorterTemplate with custom {@link Comparator} */
  private static <T> SorterTemplate getSorter(final T[] a, final Comparator comp) {
    return new SorterTemplate() {
      @Override
      protected void swap(int i, int j) {
        final T o = a[i];
        a[i] = a[j];
        a[j] = o;
      }
      
      @Override
      protected int compare(int i, int j) {
        return comp.compare(a[i], a[j]);
      }

      @Override
      protected void setPivot(int i) {
        pivot = a[i];
      }
  
      @Override
      protected int comparePivot(int j) {
        return comp.compare(pivot, a[j]);
      }
      
      private T pivot;
    };
  }
  
  /** Natural SorterTemplate */
  private static <T extends Comparable SorterTemplate getSorter(final T[] a) {
    return new SorterTemplate() {
      @Override
      protected void swap(int i, int j) {
        final T o = a[i];
        a[i] = a[j];
        a[j] = o;
      }
      
      @Override
      protected int compare(int i, int j) {
        return a[i].compareTo(a[j]);
      }

      @Override
      protected void setPivot(int i) {
        pivot = a[i];
      }
  
      @Override
      protected int comparePivot(int j) {
        return pivot.compareTo(a[j]);
      }
      
      private T pivot;
    };
  }

  // quickSorts (endindex is exclusive!):
  
  /**
   * Sorts the given array slice using the {@link Comparator}. This method uses the quick sort
   * algorithm, but falls back to insertion sort for small arrays.
   * @param fromIndex start index (inclusive)
   * @param toIndex end index (exclusive)
   */
  public static <T> void quickSort(T[] a, int fromIndex, int toIndex, Comparator comp) {
    if (toIndex-fromIndex <= 1) return;
    getSorter(a, comp).quickSort(fromIndex, toIndex-1);
  }
  
  /**
   * Sorts the given array using the {@link Comparator}. This method uses the quick sort
   * algorithm, but falls back to insertion sort for small arrays.
   */
  public static <T> void quickSort(T[] a, Comparator comp) {
    quickSort(a, 0, a.length, comp);
  }
  
  /**
   * Sorts the given array slice in natural order. This method uses the quick sort
   * algorithm, but falls back to insertion sort for small arrays.
   * @param fromIndex start index (inclusive)
   * @param toIndex end index (exclusive)
   */
  public static <T extends Comparable void quickSort(T[] a, int fromIndex, int toIndex) {
    if (toIndex-fromIndex <= 1) return;
    getSorter(a).quickSort(fromIndex, toIndex-1);
  }
  
  /**
   * Sorts the given array in natural order. This method uses the quick sort
   * algorithm, but falls back to insertion sort for small arrays.
   */
  public static <T extends Comparable void quickSort(T[] a) {
    quickSort(a, 0, a.length);
  }

  // mergeSorts:
  
  /**
   * Sorts the given array slice using the {@link Comparator}. This method uses the merge sort
   * algorithm, but falls back to insertion sort for small arrays.
   * @param fromIndex start index (inclusive)
   * @param toIndex end index (exclusive)
   */
  public static <T> void mergeSort(T[] a, int fromIndex, int toIndex, Comparator comp) {
    if (toIndex-fromIndex <= 1) return;
    getSorter(a, comp).mergeSort(fromIndex, toIndex-1);
  }
  
  /**
   * Sorts the given array using the {@link Comparator}. This method uses the merge sort
   * algorithm, but falls back to insertion sort for small arrays.
   */
  public static <T> void mergeSort(T[] a, Comparator comp) {
    mergeSort(a, 0, a.length, comp);
  }
  
  /**
   * Sorts the given array slice in natural order. This method uses the merge sort
   * algorithm, but falls back to insertion sort for small arrays.
   * @param fromIndex start index (inclusive)
   * @param toIndex end index (exclusive)
   */
  public static <T extends Comparable void mergeSort(T[] a, int fromIndex, int toIndex) {
    if (toIndex-fromIndex <= 1) return;
    getSorter(a).mergeSort(fromIndex, toIndex-1);
  }
  
  /**
   * Sorts the given array in natural order. This method uses the merge sort
   * algorithm, but falls back to insertion sort for small arrays.
   */
  public static <T extends Comparable void mergeSort(T[] a) {
    mergeSort(a, 0, a.length);
  }

  // insertionSorts:
  
  /**
   * Sorts the given array slice using the {@link Comparator}. This method uses the insertion sort
   * algorithm. It is only recommended to use this algorithm for partially sorted small arrays!
   * @param fromIndex start index (inclusive)
   * @param toIndex end index (exclusive)
   */
  public static <T> void insertionSort(T[] a, int fromIndex, int toIndex, Comparator comp) {
    if (toIndex-fromIndex <= 1) return;
    getSorter(a, comp).insertionSort(fromIndex, toIndex-1);
  }
  
  /**
   * Sorts the given array using the {@link Comparator}. This method uses the insertion sort
   * algorithm. It is only recommended to use this algorithm for partially sorted small arrays!
   */
  public static <T> void insertionSort(T[] a, Comparator comp) {
    insertionSort(a, 0, a.length, comp);
  }
  
  /**
   * Sorts the given array slice in natural order. This method uses the insertion sort
   * algorithm. It is only recommended to use this algorithm for partially sorted small arrays!
   * @param fromIndex start index (inclusive)
   * @param toIndex end index (exclusive)
   */
  public static <T extends Comparable void insertionSort(T[] a, int fromIndex, int toIndex) {
    if (toIndex-fromIndex <= 1) return;
    getSorter(a).insertionSort(fromIndex, toIndex-1);
  }
  
  /**
   * Sorts the given array in natural order. This method uses the insertion sort
   * algorithm. It is only recommended to use this algorithm for partially sorted small arrays!
   */
  public static <T extends Comparable void insertionSort(T[] a) {
    insertionSort(a, 0, a.length);
  }

}

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