263 lines
8.4 KiB
Java
263 lines
8.4 KiB
Java
/*
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* Copyright (C) 2009 The Guava Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.common.primitives;
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import static com.google.common.base.Preconditions.checkArgument;
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import static com.google.common.base.Preconditions.checkNotNull;
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import com.google.common.annotations.Beta;
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/**
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* Static utility methods pertaining to {@code byte} primitives that interpret
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* values as <i>unsigned</i> (that is, any negative value {@code b} is treated
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* as the positive value {@code 256 + b}). The corresponding methods that treat
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* the values as signed are found in {@link SignedBytes}, and the methods for
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* which signedness is not an issue are in {@link Bytes}.
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*
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* <p>
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* See the Guava User Guide article on
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* <a href= "http://code.google.com/p/guava-libraries/wiki/PrimitivesExplained">
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* primitive utilities</a>.
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*
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* @author Kevin Bourrillion
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* @author Martin Buchholz
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* @author Hiroshi Yamauchi
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* @author Louis Wasserman
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* @since 1.0
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*/
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public final class UnsignedBytes {
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private UnsignedBytes() {
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}
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/**
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* The largest power of two that can be represented as an unsigned {@code
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* byte}.
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*
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* @since 10.0
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*/
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public static final byte MAX_POWER_OF_TWO = (byte) 0x80;
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/**
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* The largest value that fits into an unsigned byte.
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*
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* @since 13.0
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*/
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public static final byte MAX_VALUE = (byte) 0xFF;
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private static final int UNSIGNED_MASK = 0xFF;
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/**
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* Returns the value of the given byte as an integer, when treated as unsigned.
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* That is, returns {@code value + 256} if {@code value} is negative;
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* {@code value} itself otherwise.
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*
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* @since 6.0
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*/
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public static int toInt(byte value) {
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return value & UNSIGNED_MASK;
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}
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/**
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* Returns the {@code byte} value that, when treated as unsigned, is equal to
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* {@code value}, if possible.
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*
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* @param value a value between 0 and 255 inclusive
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* @return the {@code byte} value that, when treated as unsigned, equals
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* {@code value}
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* @throws IllegalArgumentException if {@code value} is negative or greater than
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* 255
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*/
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public static byte checkedCast(long value) {
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if ((value >> Byte.SIZE) != 0) {
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// don't use checkArgument here, to avoid boxing
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throw new IllegalArgumentException("Out of range: " + value);
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}
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return (byte) value;
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}
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/**
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* Returns the {@code byte} value that, when treated as unsigned, is nearest in
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* value to {@code value}.
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*
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* @param value any {@code long} value
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* @return {@code (byte) 255} if {@code value >= 255}, {@code (byte) 0} if
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* {@code value <= 0}, and {@code value} cast to {@code byte} otherwise
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*/
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public static byte saturatedCast(long value) {
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if (value > toInt(MAX_VALUE)) {
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return MAX_VALUE; // -1
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}
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if (value < 0) {
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return (byte) 0;
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}
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return (byte) value;
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}
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/**
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* Compares the two specified {@code byte} values, treating them as unsigned
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* values between 0 and 255 inclusive. For example, {@code (byte) -127} is
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* considered greater than {@code (byte) 127} because it is seen as having the
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* value of positive {@code 129}.
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*
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* @param a the first {@code byte} to compare
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* @param b the second {@code byte} to compare
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* @return a negative value if {@code a} is less than {@code b}; a positive
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* value if {@code a} is greater than {@code b}; or zero if they are
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* equal
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*/
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public static int compare(byte a, byte b) {
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return toInt(a) - toInt(b);
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}
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/**
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* Returns the least value present in {@code array}.
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*
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* @param array a <i>nonempty</i> array of {@code byte} values
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* @return the value present in {@code array} that is less than or equal to
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* every other value in the array
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* @throws IllegalArgumentException if {@code array} is empty
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*/
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public static byte min(byte... array) {
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checkArgument(array.length > 0);
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int min = toInt(array[0]);
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for (int i = 1; i < array.length; i++) {
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int next = toInt(array[i]);
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if (next < min) {
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min = next;
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}
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}
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return (byte) min;
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}
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/**
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* Returns the greatest value present in {@code array}.
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*
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* @param array a <i>nonempty</i> array of {@code byte} values
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* @return the value present in {@code array} that is greater than or equal to
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* every other value in the array
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* @throws IllegalArgumentException if {@code array} is empty
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*/
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public static byte max(byte... array) {
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checkArgument(array.length > 0);
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int max = toInt(array[0]);
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for (int i = 1; i < array.length; i++) {
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int next = toInt(array[i]);
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if (next > max) {
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max = next;
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}
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}
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return (byte) max;
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}
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/**
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* Returns a string representation of x, where x is treated as unsigned.
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*
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* @since 13.0
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*/
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@Beta
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public static String toString(byte x) {
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return toString(x, 10);
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}
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/**
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* Returns a string representation of {@code x} for the given radix, where
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* {@code x} is treated as unsigned.
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*
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* @param x the value to convert to a string.
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* @param radix the radix to use while working with {@code x}
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* @throws IllegalArgumentException if {@code radix} is not between
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* {@link Character#MIN_RADIX} and
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* {@link Character#MAX_RADIX}.
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* @since 13.0
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*/
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@Beta
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public static String toString(byte x, int radix) {
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checkArgument(radix >= Character.MIN_RADIX && radix <= Character.MAX_RADIX,
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"radix (%s) must be between Character.MIN_RADIX and Character.MAX_RADIX", radix);
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// Benchmarks indicate this is probably not worth optimizing.
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return Integer.toString(toInt(x), radix);
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}
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/**
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* Returns the unsigned {@code byte} value represented by the given decimal
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* string.
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*
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* @throws NumberFormatException if the string does not contain a valid unsigned
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* {@code byte} value
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* @throws NullPointerException if {@code s} is null (in contrast to
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* {@link Byte#parseByte(String)})
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* @since 13.0
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*/
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@Beta
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public static byte parseUnsignedByte(String string) {
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return parseUnsignedByte(string, 10);
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}
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/**
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* Returns the unsigned {@code byte} value represented by a string with the
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* given radix.
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*
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* @param string the string containing the unsigned {@code byte} representation
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* to be parsed.
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* @param radix the radix to use while parsing {@code string}
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* @throws NumberFormatException if the string does not contain a valid unsigned
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* {@code byte} with the given radix, or if
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* {@code radix} is not between
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* {@link Character#MIN_RADIX} and
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* {@link Character#MAX_RADIX}.
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* @throws NullPointerException if {@code s} is null (in contrast to
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* {@link Byte#parseByte(String)})
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* @since 13.0
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*/
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@Beta
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public static byte parseUnsignedByte(String string, int radix) {
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int parse = Integer.parseInt(checkNotNull(string), radix);
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// We need to throw a NumberFormatException, so we have to duplicate
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// checkedCast. =(
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if (parse >> Byte.SIZE == 0) {
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return (byte) parse;
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} else {
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throw new NumberFormatException("out of range: " + parse);
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}
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}
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/**
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* Returns a string containing the supplied {@code byte} values separated by
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* {@code separator}. For example, {@code join(":", (byte) 1, (byte) 2,
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* (byte) 255)} returns the string {@code "1:2:255"}.
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*
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* @param separator the text that should appear between consecutive values in
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* the resulting string (but not at the start or end)
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* @param array an array of {@code byte} values, possibly empty
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*/
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public static String join(String separator, byte... array) {
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checkNotNull(separator);
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if (array.length == 0) {
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return "";
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}
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// For pre-sizing a builder, just get the right order of magnitude
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StringBuilder builder = new StringBuilder(array.length * (3 + separator.length()));
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builder.append(toInt(array[0]));
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for (int i = 1; i < array.length; i++) {
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builder.append(separator).append(toString(array[i]));
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}
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return builder.toString();
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}
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}
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