/* * 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.GwtCompatible; import com.google.common.annotations.GwtIncompatible; 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 long} primitives, that are not * already found in either {@link Long} or {@link Arrays}. * * @author Kevin Bourrillion * @since 1.0 */ @GwtCompatible(emulated = true) public final class Longs { private Longs() {} /** * The number of bytes required to represent a primitive {@code long} * value. */ public static final int BYTES = Long.SIZE / Byte.SIZE; /** * The largest power of two that can be represented as a {@code long}. * * @since 10.0 */ public static final long MAX_POWER_OF_TWO = 1L << (Long.SIZE - 2); /** * Returns a hash code for {@code value}; equal to the result of invoking * {@code ((Long) value).hashCode()}. * *
This method always return the value specified by {@link * Long#hashCode()} in java, which might be different from * {@code ((Long) value).hashCode()} in GWT because {@link Long#hashCode()} * in GWT does not obey the JRE contract. * * @param value a primitive {@code long} value * @return a hash code for the value */ public static int hashCode(long value) { return (int) (value ^ (value >>> 32)); } /** * Compares the two specified {@code long} values. The sign of the value * returned is the same as that of {@code ((Long) a).compareTo(b)}. * * @param a the first {@code long} to compare * @param b the second {@code long} 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(long a, long b) { return (a < b) ? -1 : ((a > b) ? 1 : 0); } /** * Returns {@code true} if {@code target} is present as an element anywhere in * {@code array}. * * @param array an array of {@code long} values, possibly empty * @param target a primitive {@code long} value * @return {@code true} if {@code array[i] == target} for some value of {@code * i} */ public static boolean contains(long[] array, long target) { for (long 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 long} values, possibly empty * @param target a primitive {@code long} 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(long[] array, long target) { return indexOf(array, target, 0, array.length); } // TODO(kevinb): consider making this public private static int indexOf( long[] array, long 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. * *
More formally, returns the lowest index {@code i} such that {@code * java.util.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(long[] array, long[] 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 long} values, possibly empty * @param target a primitive {@code long} 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(long[] array, long target) { return lastIndexOf(array, target, 0, array.length); } // TODO(kevinb): consider making this public private static int lastIndexOf( long[] array, long 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 nonempty array of {@code long} 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 long min(long... array) { checkArgument(array.length > 0); long 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 nonempty array of {@code long} 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 long max(long... array) { checkArgument(array.length > 0); long 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 long[] {a, b}, new long[] {}, new * long[] {c}} returns the array {@code {a, b, c}}. * * @param arrays zero or more {@code long} arrays * @return a single array containing all the values from the source arrays, in * order */ public static long[] concat(long[]... arrays) { int length = 0; for (long[] array : arrays) { length += array.length; } long[] result = new long[length]; int pos = 0; for (long[] array : arrays) { System.arraycopy(array, 0, result, pos, array.length); pos += array.length; } return result; } /** * Returns a big-endian representation of {@code value} in an 8-element byte * array; equivalent to {@code ByteBuffer.allocate(8).putLong(value).array()}. * For example, the input value {@code 0x1213141516171819L} would yield the * byte array {@code {0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19}}. * *
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(long value) { return new byte[] { (byte) (value >> 56), (byte) (value >> 48), (byte) (value >> 40), (byte) (value >> 32), (byte) (value >> 24), (byte) (value >> 16), (byte) (value >> 8), (byte) value}; } /** * Returns the {@code long} value whose big-endian representation is * stored in the first 8 bytes of {@code bytes}; equivalent to {@code * ByteBuffer.wrap(bytes).getLong()}. For example, the input byte array * {@code {0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19}} would yield the * {@code long} value {@code 0x1213141516171819L}. * *
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 8 * elements */ @GwtIncompatible("doesn't work") public static long fromByteArray(byte[] bytes) { checkArgument(bytes.length >= BYTES, "array too small: %s < %s", bytes.length, BYTES); return fromBytes(bytes[0], bytes[1], bytes[2], bytes[3], bytes[4], bytes[5], bytes[6], bytes[7]) ; } /** * Returns the {@code long} value whose byte representation is the given 8 * bytes, in big-endian order; equivalent to {@code Longs.fromByteArray(new * byte[] {b1, b2, b3, b4, b5, b6, b7, b8})}. * * @since 7.0 */ @GwtIncompatible("doesn't work") public static long fromBytes(byte b1, byte b2, byte b3, byte b4, byte b5, byte b6, byte b7, byte b8) { return (b1 & 0xFFL) << 56 | (b2 & 0xFFL) << 48 | (b3 & 0xFFL) << 40 | (b4 & 0xFFL) << 32 | (b5 & 0xFFL) << 24 | (b6 & 0xFFL) << 16 | (b7 & 0xFFL) << 8 | (b8 & 0xFFL); } /** * 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 long[] ensureCapacity( long[] array, int minLength, int padding) { checkArgument(minLength >= 0, "Invalid minLength: %s", minLength); checkArgument(padding >= 0, "Invalid padding: %s", padding); return (array.length < minLength) ? copyOf(array, minLength + padding) : array; } // Arrays.copyOf() requires Java 6 private static long[] copyOf(long[] original, int length) { long[] copy = new long[length]; System.arraycopy(original, 0, copy, 0, Math.min(original.length, length)); return copy; } /** * Returns a string containing the supplied {@code long} values separated * by {@code separator}. For example, {@code join("-", 1L, 2L, 3L)} 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 long} values, possibly empty */ public static String join(String separator, long... 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 * 10); 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 long} arrays * lexicographically. That is, it compares, using {@link * #compare(long, long)}), 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 [] < [1L] < [1L, 2L] < [2L]}. * *
The returned comparator is inconsistent with {@link
* Object#equals(Object)} (since arrays support only identity equality), but
* it is consistent with {@link Arrays#equals(long[], long[])}.
*
* @see
* Lexicographical order article at Wikipedia
* @since 2.0
*/
public static Comparator 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 Long} objects
* @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
*/
public static long[] toArray(Collection The returned list maintains the values, but not the identities, of
* {@code Long} 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