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Java example source code file (Shorts.java)

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

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Java - Java tags/keywords

bytes, comparator, gwtincompatible, instance, invalid, number, object, override, serializable, short, shortarrayaslist, shortconverter, string, stringbuilder, util

The Shorts.java Java example source code

/*
 * Copyright (C) 2008 The Guava Authors
 *
 * Licensed 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.
 */

package com.google.common.primitives;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkElementIndex;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkPositionIndexes;

import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.base.Converter;

import java.io.Serializable;
import java.util.AbstractList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.RandomAccess;

/**
 * Static utility methods pertaining to {@code short} primitives, that are not already found in
 * either {@link Short} or {@link Arrays}.
 *
 * <p>See the Guava User Guide article on
 * <a href="https://github.com/google/guava/wiki/PrimitivesExplained">primitive utilities.
 *
 * @author Kevin Bourrillion
 * @since 1.0
 */
@GwtCompatible(emulated = true)
public final class Shorts {
  private Shorts() {}

  /**
   * The number of bytes required to represent a primitive {@code short} value.
   */
  public static final int BYTES = Short.SIZE / Byte.SIZE;

  /**
   * The largest power of two that can be represented as a {@code short}.
   *
   * @since 10.0
   */
  public static final short MAX_POWER_OF_TWO = 1 << (Short.SIZE - 2);

  /**
   * Returns a hash code for {@code value}; equal to the result of invoking
   * {@code ((Short) value).hashCode()}.
   *
   * @param value a primitive {@code short} value
   * @return a hash code for the value
   */
  public static int hashCode(short value) {
    return value;
  }

  /**
   * Returns the {@code short} value that is equal to {@code value}, if possible.
   *
   * @param value any value in the range of the {@code short} type
   * @return the {@code short} value that equals {@code value}
   * @throws IllegalArgumentException if {@code value} is greater than {@link Short#MAX_VALUE} or
   *     less than {@link Short#MIN_VALUE}
   */
  public static short checkedCast(long value) {
    short result = (short) value;
    if (result != value) {
      // don't use checkArgument here, to avoid boxing
      throw new IllegalArgumentException("Out of range: " + value);
    }
    return result;
  }

  /**
   * Returns the {@code short} nearest in value to {@code value}.
   *
   * @param value any {@code long} value
   * @return the same value cast to {@code short} if it is in the range of the {@code short} type,
   *     {@link Short#MAX_VALUE} if it is too large, or {@link Short#MIN_VALUE} if it is too small
   */
  public static short saturatedCast(long value) {
    if (value > Short.MAX_VALUE) {
      return Short.MAX_VALUE;
    }
    if (value < Short.MIN_VALUE) {
      return Short.MIN_VALUE;
    }
    return (short) value;
  }

  /**
   * Compares the two specified {@code short} values. The sign of the value returned is the same as
   * that of {@code ((Short) a).compareTo(b)}.
   *
   * <p>Note for Java 7 and later: this method should be treated as deprecated; use the
   * equivalent {@link Short#compare} method instead.
   *
   * @param a the first {@code short} to compare
   * @param b the second {@code short} to compare
   * @return a negative value if {@code a} is less than {@code b}; a positive value if {@code a} is
   *     greater than {@code b}; or zero if they are equal
   */
  public static int compare(short a, short b) {
    return a - b; // safe due to restricted range
  }

  /**
   * Returns {@code true} if {@code target} is present as an element anywhere in {@code array}.
   *
   * @param array an array of {@code short} values, possibly empty
   * @param target a primitive {@code short} value
   * @return {@code true} if {@code array[i] == target} for some value of {@code
   *     i}
   */
  public static boolean contains(short[] array, short target) {
    for (short value : array) {
      if (value == target) {
        return true;
      }
    }
    return false;
  }

  /**
   * Returns the index of the first appearance of the value {@code target} in {@code array}.
   *
   * @param array an array of {@code short} values, possibly empty
   * @param target a primitive {@code short} value
   * @return the least index {@code i} for which {@code array[i] == target}, or {@code -1} if no
   *     such index exists.
   */
  public static int indexOf(short[] array, short target) {
    return indexOf(array, target, 0, array.length);
  }

  // TODO(kevinb): consider making this public
  private static int indexOf(short[] array, short target, int start, int end) {
    for (int i = start; i < end; i++) {
      if (array[i] == target) {
        return i;
      }
    }
    return -1;
  }

  /**
   * Returns the start position of the first occurrence of the specified {@code
   * target} within {@code array}, or {@code -1} if there is no such occurrence.
   *
   * <p>More formally, returns the lowest index {@code i} such that
   * {@code Arrays.copyOfRange(array, i, i + target.length)} contains exactly the same elements as
   * {@code target}.
   *
   * @param array the array to search for the sequence {@code target}
   * @param target the array to search for as a sub-sequence of {@code array}
   */
  public static int indexOf(short[] array, short[] target) {
    checkNotNull(array, "array");
    checkNotNull(target, "target");
    if (target.length == 0) {
      return 0;
    }

    outer:
    for (int i = 0; i < array.length - target.length + 1; i++) {
      for (int j = 0; j < target.length; j++) {
        if (array[i + j] != target[j]) {
          continue outer;
        }
      }
      return i;
    }
    return -1;
  }

  /**
   * Returns the index of the last appearance of the value {@code target} in {@code array}.
   *
   * @param array an array of {@code short} values, possibly empty
   * @param target a primitive {@code short} value
   * @return the greatest index {@code i} for which {@code array[i] == target}, or {@code -1} if no
   *     such index exists.
   */
  public static int lastIndexOf(short[] array, short target) {
    return lastIndexOf(array, target, 0, array.length);
  }

  // TODO(kevinb): consider making this public
  private static int lastIndexOf(short[] array, short target, int start, int end) {
    for (int i = end - 1; i >= start; i--) {
      if (array[i] == target) {
        return i;
      }
    }
    return -1;
  }

  /**
   * Returns the least value present in {@code array}.
   *
   * @param array a <i>nonempty array of {@code short} values
   * @return the value present in {@code array} that is less than or equal to every other value in
   *     the array
   * @throws IllegalArgumentException if {@code array} is empty
   */
  public static short min(short... array) {
    checkArgument(array.length > 0);
    short min = array[0];
    for (int i = 1; i < array.length; i++) {
      if (array[i] < min) {
        min = array[i];
      }
    }
    return min;
  }

  /**
   * Returns the greatest value present in {@code array}.
   *
   * @param array a <i>nonempty array of {@code short} values
   * @return the value present in {@code array} that is greater than or equal to every other value
   *     in the array
   * @throws IllegalArgumentException if {@code array} is empty
   */
  public static short max(short... array) {
    checkArgument(array.length > 0);
    short max = array[0];
    for (int i = 1; i < array.length; i++) {
      if (array[i] > max) {
        max = array[i];
      }
    }
    return max;
  }

  /**
   * Returns the values from each provided array combined into a single array. For example,
   * {@code concat(new short[] {a, b}, new short[] {}, new short[] {c}} returns the array
   * {@code {a, b, c}}.
   *
   * @param arrays zero or more {@code short} arrays
   * @return a single array containing all the values from the source arrays, in order
   */
  public static short[] concat(short[]... arrays) {
    int length = 0;
    for (short[] array : arrays) {
      length += array.length;
    }
    short[] result = new short[length];
    int pos = 0;
    for (short[] array : arrays) {
      System.arraycopy(array, 0, result, pos, array.length);
      pos += array.length;
    }
    return result;
  }

  /**
   * Returns a big-endian representation of {@code value} in a 2-element byte array; equivalent to
   * {@code ByteBuffer.allocate(2).putShort(value).array()}. For example, the input value {@code
   * (short) 0x1234} would yield the byte array {@code {0x12, 0x34}}.
   *
   * <p>If you need to convert and concatenate several values (possibly even of different types),
   * use a shared {@link java.nio.ByteBuffer} instance, or use
   * {@link com.google.common.io.ByteStreams#newDataOutput()} to get a growable buffer.
   */
  @GwtIncompatible // doesn't work
  public static byte[] toByteArray(short value) {
    return new byte[] {(byte) (value >> 8), (byte) value};
  }

  /**
   * Returns the {@code short} value whose big-endian representation is stored in the first 2 bytes
   * of {@code bytes}; equivalent to {@code ByteBuffer.wrap(bytes).getShort()}. For example, the
   * input byte array {@code {0x54, 0x32}} would yield the {@code short} value {@code 0x5432}.
   *
   * <p>Arguably, it's preferable to use {@link java.nio.ByteBuffer}; that library exposes much more
   * flexibility at little cost in readability.
   *
   * @throws IllegalArgumentException if {@code bytes} has fewer than 2 elements
   */
  @GwtIncompatible // doesn't work
  public static short fromByteArray(byte[] bytes) {
    checkArgument(bytes.length >= BYTES, "array too small: %s < %s", bytes.length, BYTES);
    return fromBytes(bytes[0], bytes[1]);
  }

  /**
   * Returns the {@code short} value whose byte representation is the given 2 bytes, in big-endian
   * order; equivalent to {@code Shorts.fromByteArray(new byte[] {b1, b2})}.
   *
   * @since 7.0
   */
  @GwtIncompatible // doesn't work
  public static short fromBytes(byte b1, byte b2) {
    return (short) ((b1 << 8) | (b2 & 0xFF));
  }

  private static final class ShortConverter extends Converter<String, Short>
      implements Serializable {
    static final ShortConverter INSTANCE = new ShortConverter();

    @Override
    protected Short doForward(String value) {
      return Short.decode(value);
    }

    @Override
    protected String doBackward(Short value) {
      return value.toString();
    }

    @Override
    public String toString() {
      return "Shorts.stringConverter()";
    }

    private Object readResolve() {
      return INSTANCE;
    }

    private static final long serialVersionUID = 1;
  }

  /**
   * Returns a serializable converter object that converts between strings and shorts using
   * {@link Short#decode} and {@link Short#toString()}. The returned converter throws
   * {@link NumberFormatException} if the input string is invalid.
   *
   * <p>Warning: please see {@link Short#decode} to understand exactly how strings are
   * parsed. For example, the string {@code "0123"} is treated as <i>octal and converted to the
   * value {@code 83}.
   *
   * @since 16.0
   */
  @Beta
  public static Converter<String, Short> stringConverter() {
    return ShortConverter.INSTANCE;
  }

  /**
   * Returns an array containing the same values as {@code array}, but guaranteed to be of a
   * specified minimum length. If {@code array} already has a length of at least {@code minLength},
   * it is returned directly. Otherwise, a new array of size {@code minLength + padding} is
   * returned, containing the values of {@code array}, and zeroes in the remaining places.
   *
   * @param array the source array
   * @param minLength the minimum length the returned array must guarantee
   * @param padding an extra amount to "grow" the array by if growth is necessary
   * @throws IllegalArgumentException if {@code minLength} or {@code padding} is negative
   * @return an array containing the values of {@code array}, with guaranteed minimum length
   *     {@code minLength}
   */
  public static short[] ensureCapacity(short[] array, int minLength, int padding) {
    checkArgument(minLength >= 0, "Invalid minLength: %s", minLength);
    checkArgument(padding >= 0, "Invalid padding: %s", padding);
    return (array.length < minLength) ? Arrays.copyOf(array, minLength + padding) : array;
  }

  /**
   * Returns a string containing the supplied {@code short} values separated by {@code separator}.
   * For example, {@code join("-", (short) 1, (short) 2,
   * (short) 3)} returns the string {@code "1-2-3"}.
   *
   * @param separator the text that should appear between consecutive values in the resulting string
   *     (but not at the start or end)
   * @param array an array of {@code short} values, possibly empty
   */
  public static String join(String separator, short... array) {
    checkNotNull(separator);
    if (array.length == 0) {
      return "";
    }

    // For pre-sizing a builder, just get the right order of magnitude
    StringBuilder builder = new StringBuilder(array.length * 6);
    builder.append(array[0]);
    for (int i = 1; i < array.length; i++) {
      builder.append(separator).append(array[i]);
    }
    return builder.toString();
  }

  /**
   * Returns a comparator that compares two {@code short} arrays <a
   * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. That is, it
   * compares, using {@link #compare(short, short)}), the first pair of values that follow any
   * common prefix, or when one array is a prefix of the other, treats the shorter array as the
   * lesser. For example, {@code [] < [(short) 1] < [(short) 1, (short) 2] < [(short) 2]}.
   *
   * <p>The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays
   * support only identity equality), but it is consistent with
   * {@link Arrays#equals(short[], short[])}.
   *
   * @since 2.0
   */
  public static Comparator<short[]> lexicographicalComparator() {
    return LexicographicalComparator.INSTANCE;
  }

  private enum LexicographicalComparator implements Comparator<short[]> {
    INSTANCE;

    @Override
    public int compare(short[] left, short[] right) {
      int minLength = Math.min(left.length, right.length);
      for (int i = 0; i < minLength; i++) {
        int result = Shorts.compare(left[i], right[i]);
        if (result != 0) {
          return result;
        }
      }
      return left.length - right.length;
    }

    @Override
    public String toString() {
      return "Shorts.lexicographicalComparator()";
    }
  }

  /**
   * Returns an array containing each value of {@code collection}, converted to a {@code short}
   * value in the manner of {@link Number#shortValue}.
   *
   * <p>Elements are copied from the argument collection as if by {@code
   * collection.toArray()}. Calling this method is as thread-safe as calling that method.
   *
   * @param collection a collection of {@code Number} instances
   * @return an array containing the same values as {@code collection}, in the same order, converted
   *     to primitives
   * @throws NullPointerException if {@code collection} or any of its elements is null
   * @since 1.0 (parameter was {@code Collection<Short>} before 12.0)
   */
  public static short[] toArray(Collection<? extends Number> collection) {
    if (collection instanceof ShortArrayAsList) {
      return ((ShortArrayAsList) collection).toShortArray();
    }

    Object[] boxedArray = collection.toArray();
    int len = boxedArray.length;
    short[] array = new short[len];
    for (int i = 0; i < len; i++) {
      // checkNotNull for GWT (do not optimize)
      array[i] = ((Number) checkNotNull(boxedArray[i])).shortValue();
    }
    return array;
  }

  /**
   * Returns a fixed-size list backed by the specified array, similar to
   * {@link Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)}, but any
   * attempt to set a value to {@code null} will result in a {@link NullPointerException}.
   *
   * <p>The returned list maintains the values, but not the identities, of {@code Short} objects
   * written to or read from it. For example, whether {@code list.get(0) == list.get(0)} is true for
   * the returned list is unspecified.
   *
   * @param backingArray the array to back the list
   * @return a list view of the array
   */
  public static List<Short> asList(short... backingArray) {
    if (backingArray.length == 0) {
      return Collections.emptyList();
    }
    return new ShortArrayAsList(backingArray);
  }

  @GwtCompatible
  private static class ShortArrayAsList extends AbstractList<Short>
      implements RandomAccess, Serializable {
    final short[] array;
    final int start;
    final int end;

    ShortArrayAsList(short[] array) {
      this(array, 0, array.length);
    }

    ShortArrayAsList(short[] array, int start, int end) {
      this.array = array;
      this.start = start;
      this.end = end;
    }

    @Override
    public int size() {
      return end - start;
    }

    @Override
    public boolean isEmpty() {
      return false;
    }

    @Override
    public Short get(int index) {
      checkElementIndex(index, size());
      return array[start + index];
    }

    @Override
    public boolean contains(Object target) {
      // Overridden to prevent a ton of boxing
      return (target instanceof Short) && Shorts.indexOf(array, (Short) target, start, end) != -1;
    }

    @Override
    public int indexOf(Object target) {
      // Overridden to prevent a ton of boxing
      if (target instanceof Short) {
        int i = Shorts.indexOf(array, (Short) target, start, end);
        if (i >= 0) {
          return i - start;
        }
      }
      return -1;
    }

    @Override
    public int lastIndexOf(Object target) {
      // Overridden to prevent a ton of boxing
      if (target instanceof Short) {
        int i = Shorts.lastIndexOf(array, (Short) target, start, end);
        if (i >= 0) {
          return i - start;
        }
      }
      return -1;
    }

    @Override
    public Short set(int index, Short element) {
      checkElementIndex(index, size());
      short oldValue = array[start + index];
      // checkNotNull for GWT (do not optimize)
      array[start + index] = checkNotNull(element);
      return oldValue;
    }

    @Override
    public List<Short> subList(int fromIndex, int toIndex) {
      int size = size();
      checkPositionIndexes(fromIndex, toIndex, size);
      if (fromIndex == toIndex) {
        return Collections.emptyList();
      }
      return new ShortArrayAsList(array, start + fromIndex, start + toIndex);
    }

    @Override
    public boolean equals(Object object) {
      if (object == this) {
        return true;
      }
      if (object instanceof ShortArrayAsList) {
        ShortArrayAsList that = (ShortArrayAsList) object;
        int size = size();
        if (that.size() != size) {
          return false;
        }
        for (int i = 0; i < size; i++) {
          if (array[start + i] != that.array[that.start + i]) {
            return false;
          }
        }
        return true;
      }
      return super.equals(object);
    }

    @Override
    public int hashCode() {
      int result = 1;
      for (int i = start; i < end; i++) {
        result = 31 * result + Shorts.hashCode(array[i]);
      }
      return result;
    }

    @Override
    public String toString() {
      StringBuilder builder = new StringBuilder(size() * 6);
      builder.append('[').append(array[start]);
      for (int i = start + 1; i < end; i++) {
        builder.append(", ").append(array[i]);
      }
      return builder.append(']').toString();
    }

    short[] toShortArray() {
      // Arrays.copyOfRange() is not available under GWT
      int size = size();
      short[] result = new short[size];
      System.arraycopy(array, start, result, 0, size);
      return result;
    }

    private static final long serialVersionUID = 0;
  }
}

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