Java tutorial
/* * Copyright (c) 1996, 2019, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.lang; import jdk.internal.HotSpotIntrinsicCandidate; import jdk.internal.misc.VM; /** * The {@code Short} class wraps a value of primitive type {@code * short} in an object. An object of type {@code Short} contains a * single field whose type is {@code short}. * * <p>In addition, this class provides several methods for converting * a {@code short} to a {@code String} and a {@code String} to a * {@code short}, as well as other constants and methods useful when * dealing with a {@code short}. * * @author Nakul Saraiya * @author Joseph D. Darcy * @see java.lang.Number * @since 1.1 */ public final class Short extends Number implements Comparable<Short> { /** * A constant holding the minimum value a {@code short} can * have, -2<sup>15</sup>. */ public static final short MIN_VALUE = -32768; /** * A constant holding the maximum value a {@code short} can * have, 2<sup>15</sup>-1. */ public static final short MAX_VALUE = 32767; /** * The {@code Class} instance representing the primitive type * {@code short}. */ @SuppressWarnings("unchecked") public static final Class<Short> TYPE = (Class<Short>) Class.getPrimitiveClass("short"); /** * Returns a new {@code String} object representing the * specified {@code short}. The radix is assumed to be 10. * * @param s the {@code short} to be converted * @return the string representation of the specified {@code short} * @see java.lang.Integer#toString(int) */ public static String toString(short s) { return Integer.toString((int) s, 10); } /** * Parses the string argument as a signed {@code short} in the * radix specified by the second argument. The characters in the * string must all be digits, of the specified radix (as * determined by whether {@link java.lang.Character#digit(char, * int)} returns a nonnegative value) except that the first * character may be an ASCII minus sign {@code '-'} * ({@code '\u005Cu002D'}) to indicate a negative value or an * ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to * indicate a positive value. The resulting {@code short} value * is returned. * * <p>An exception of type {@code NumberFormatException} is * thrown if any of the following situations occurs: * <ul> * <li> The first argument is {@code null} or is a string of * length zero. * * <li> The radix is either smaller than {@link * java.lang.Character#MIN_RADIX} or larger than {@link * java.lang.Character#MAX_RADIX}. * * <li> Any character of the string is not a digit of the * specified radix, except that the first character may be a minus * sign {@code '-'} ({@code '\u005Cu002D'}) or plus sign * {@code '+'} ({@code '\u005Cu002B'}) provided that the * string is longer than length 1. * * <li> The value represented by the string is not a value of type * {@code short}. * </ul> * * @param s the {@code String} containing the * {@code short} representation to be parsed * @param radix the radix to be used while parsing {@code s} * @return the {@code short} represented by the string * argument in the specified radix. * @throws NumberFormatException If the {@code String} * does not contain a parsable {@code short}. */ public static short parseShort(String s, int radix) throws NumberFormatException { int i = Integer.parseInt(s, radix); if (i < MIN_VALUE || i > MAX_VALUE) throw new NumberFormatException("Value out of range. Value:\"" + s + "\" Radix:" + radix); return (short) i; } /** * Parses the string argument as a signed decimal {@code * short}. The characters in the string must all be decimal * digits, except that the first character may be an ASCII minus * sign {@code '-'} ({@code '\u005Cu002D'}) to indicate a * negative value or an ASCII plus sign {@code '+'} * ({@code '\u005Cu002B'}) to indicate a positive value. The * resulting {@code short} value is returned, exactly as if the * argument and the radix 10 were given as arguments to the {@link * #parseShort(java.lang.String, int)} method. * * @param s a {@code String} containing the {@code short} * representation to be parsed * @return the {@code short} value represented by the * argument in decimal. * @throws NumberFormatException If the string does not * contain a parsable {@code short}. */ public static short parseShort(String s) throws NumberFormatException { return parseShort(s, 10); } /** * Returns a {@code Short} object holding the value * extracted from the specified {@code String} when parsed * with the radix given by the second argument. The first argument * is interpreted as representing a signed {@code short} in * the radix specified by the second argument, exactly as if the * argument were given to the {@link #parseShort(java.lang.String, * int)} method. The result is a {@code Short} object that * represents the {@code short} value specified by the string. * * <p>In other words, this method returns a {@code Short} object * equal to the value of: * * <blockquote> * {@code new Short(Short.parseShort(s, radix))} * </blockquote> * * @param s the string to be parsed * @param radix the radix to be used in interpreting {@code s} * @return a {@code Short} object holding the value * represented by the string argument in the * specified radix. * @throws NumberFormatException If the {@code String} does * not contain a parsable {@code short}. */ public static Short valueOf(String s, int radix) throws NumberFormatException { return valueOf(parseShort(s, radix)); } /** * Returns a {@code Short} object holding the * value given by the specified {@code String}. The argument * is interpreted as representing a signed decimal * {@code short}, exactly as if the argument were given to * the {@link #parseShort(java.lang.String)} method. The result is * a {@code Short} object that represents the * {@code short} value specified by the string. * * <p>In other words, this method returns a {@code Short} object * equal to the value of: * * <blockquote> * {@code new Short(Short.parseShort(s))} * </blockquote> * * @param s the string to be parsed * @return a {@code Short} object holding the value * represented by the string argument * @throws NumberFormatException If the {@code String} does * not contain a parsable {@code short}. */ public static Short valueOf(String s) throws NumberFormatException { return valueOf(s, 10); } private static class ShortCache { private ShortCache() { } static final Short[] cache; static Short[] archivedCache; static { int size = -(-128) + 127 + 1; // Load and use the archived cache if it exists VM.initializeFromArchive(ShortCache.class); if (archivedCache == null || archivedCache.length != size) { Short[] c = new Short[size]; short value = -128; for (int i = 0; i < size; i++) { c[i] = new Short(value++); } archivedCache = c; } cache = archivedCache; } } /** * Returns a {@code Short} instance representing the specified * {@code short} value. * If a new {@code Short} instance is not required, this method * should generally be used in preference to the constructor * {@link #Short(short)}, as this method is likely to yield * significantly better space and time performance by caching * frequently requested values. * * This method will always cache values in the range -128 to 127, * inclusive, and may cache other values outside of this range. * * @param s a short value. * @return a {@code Short} instance representing {@code s}. * @since 1.5 */ @HotSpotIntrinsicCandidate public static Short valueOf(short s) { final int offset = 128; int sAsInt = s; if (sAsInt >= -128 && sAsInt <= 127) { // must cache return ShortCache.cache[sAsInt + offset]; } return new Short(s); } /** * Decodes a {@code String} into a {@code Short}. * Accepts decimal, hexadecimal, and octal numbers given by * the following grammar: * * <blockquote> * <dl> * <dt><i>DecodableString:</i> * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i> * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i> * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i> * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i> * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i> * * <dt><i>Sign:</i> * <dd>{@code -} * <dd>{@code +} * </dl> * </blockquote> * * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i> * are as defined in section 3.10.1 of * <cite>The Java™ Language Specification</cite>, * except that underscores are not accepted between digits. * * <p>The sequence of characters following an optional * sign and/or radix specifier ("{@code 0x}", "{@code 0X}", * "{@code #}", or leading zero) is parsed as by the {@code * Short.parseShort} method with the indicated radix (10, 16, or * 8). This sequence of characters must represent a positive * value or a {@link NumberFormatException} will be thrown. The * result is negated if first character of the specified {@code * String} is the minus sign. No whitespace characters are * permitted in the {@code String}. * * @param nm the {@code String} to decode. * @return a {@code Short} object holding the {@code short} * value represented by {@code nm} * @throws NumberFormatException if the {@code String} does not * contain a parsable {@code short}. * @see java.lang.Short#parseShort(java.lang.String, int) */ public static Short decode(String nm) throws NumberFormatException { int i = Integer.decode(nm); if (i < MIN_VALUE || i > MAX_VALUE) throw new NumberFormatException("Value " + i + " out of range from input " + nm); return valueOf((short) i); } /** * The value of the {@code Short}. * * @serial */ private final short value; /** * Constructs a newly allocated {@code Short} object that * represents the specified {@code short} value. * * @param value the value to be represented by the * {@code Short}. * * @deprecated * It is rarely appropriate to use this constructor. The static factory * {@link #valueOf(short)} is generally a better choice, as it is * likely to yield significantly better space and time performance. */ @Deprecated(since = "9") public Short(short value) { this.value = value; } /** * Constructs a newly allocated {@code Short} object that * represents the {@code short} value indicated by the * {@code String} parameter. The string is converted to a * {@code short} value in exactly the manner used by the * {@code parseShort} method for radix 10. * * @param s the {@code String} to be converted to a * {@code Short} * @throws NumberFormatException If the {@code String} * does not contain a parsable {@code short}. * * @deprecated * It is rarely appropriate to use this constructor. * Use {@link #parseShort(String)} to convert a string to a * {@code short} primitive, or use {@link #valueOf(String)} * to convert a string to a {@code Short} object. */ @Deprecated(since = "9") public Short(String s) throws NumberFormatException { this.value = parseShort(s, 10); } /** * Returns the value of this {@code Short} as a {@code byte} after * a narrowing primitive conversion. * @jls 5.1.3 Narrowing Primitive Conversion */ public byte byteValue() { return (byte) value; } /** * Returns the value of this {@code Short} as a * {@code short}. */ @HotSpotIntrinsicCandidate public short shortValue() { return value; } /** * Returns the value of this {@code Short} as an {@code int} after * a widening primitive conversion. * @jls 5.1.2 Widening Primitive Conversion */ public int intValue() { return (int) value; } /** * Returns the value of this {@code Short} as a {@code long} after * a widening primitive conversion. * @jls 5.1.2 Widening Primitive Conversion */ public long longValue() { return (long) value; } /** * Returns the value of this {@code Short} as a {@code float} * after a widening primitive conversion. * @jls 5.1.2 Widening Primitive Conversion */ public float floatValue() { return (float) value; } /** * Returns the value of this {@code Short} as a {@code double} * after a widening primitive conversion. * @jls 5.1.2 Widening Primitive Conversion */ public double doubleValue() { return (double) value; } /** * Returns a {@code String} object representing this * {@code Short}'s value. The value is converted to signed * decimal representation and returned as a string, exactly as if * the {@code short} value were given as an argument to the * {@link java.lang.Short#toString(short)} method. * * @return a string representation of the value of this object in * base 10. */ public String toString() { return Integer.toString((int) value); } /** * Returns a hash code for this {@code Short}; equal to the result * of invoking {@code intValue()}. * * @return a hash code value for this {@code Short} */ @Override public int hashCode() { return Short.hashCode(value); } /** * Returns a hash code for a {@code short} value; compatible with * {@code Short.hashCode()}. * * @param value the value to hash * @return a hash code value for a {@code short} value. * @since 1.8 */ public static int hashCode(short value) { return (int) value; } /** * Compares this object to the specified object. The result is * {@code true} if and only if the argument is not * {@code null} and is a {@code Short} object that * contains the same {@code short} value as this object. * * @param obj the object to compare with * @return {@code true} if the objects are the same; * {@code false} otherwise. */ public boolean equals(Object obj) { if (obj instanceof Short) { return value == ((Short) obj).shortValue(); } return false; } /** * Compares two {@code Short} objects numerically. * * @param anotherShort the {@code Short} to be compared. * @return the value {@code 0} if this {@code Short} is * equal to the argument {@code Short}; a value less than * {@code 0} if this {@code Short} is numerically less * than the argument {@code Short}; and a value greater than * {@code 0} if this {@code Short} is numerically * greater than the argument {@code Short} (signed * comparison). * @since 1.2 */ public int compareTo(Short anotherShort) { return compare(this.value, anotherShort.value); } /** * Compares two {@code short} values numerically. * The value returned is identical to what would be returned by: * <pre> * Short.valueOf(x).compareTo(Short.valueOf(y)) * </pre> * * @param x the first {@code short} to compare * @param y the second {@code short} to compare * @return the value {@code 0} if {@code x == y}; * a value less than {@code 0} if {@code x < y}; and * a value greater than {@code 0} if {@code x > y} * @since 1.7 */ public static int compare(short x, short y) { return x - y; } /** * Compares two {@code short} values numerically treating the values * as unsigned. * * @param x the first {@code short} to compare * @param y the second {@code short} to compare * @return the value {@code 0} if {@code x == y}; a value less * than {@code 0} if {@code x < y} as unsigned values; and * a value greater than {@code 0} if {@code x > y} as * unsigned values * @since 9 */ public static int compareUnsigned(short x, short y) { return Short.toUnsignedInt(x) - Short.toUnsignedInt(y); } /** * The number of bits used to represent a {@code short} value in two's * complement binary form. * @since 1.5 */ public static final int SIZE = 16; /** * The number of bytes used to represent a {@code short} value in two's * complement binary form. * * @since 1.8 */ public static final int BYTES = SIZE / Byte.SIZE; /** * Returns the value obtained by reversing the order of the bytes in the * two's complement representation of the specified {@code short} value. * * @param i the value whose bytes are to be reversed * @return the value obtained by reversing (or, equivalently, swapping) * the bytes in the specified {@code short} value. * @since 1.5 */ @HotSpotIntrinsicCandidate public static short reverseBytes(short i) { return (short) (((i & 0xFF00) >> 8) | (i << 8)); } /** * Converts the argument to an {@code int} by an unsigned * conversion. In an unsigned conversion to an {@code int}, the * high-order 16 bits of the {@code int} are zero and the * low-order 16 bits are equal to the bits of the {@code short} argument. * * Consequently, zero and positive {@code short} values are mapped * to a numerically equal {@code int} value and negative {@code * short} values are mapped to an {@code int} value equal to the * input plus 2<sup>16</sup>. * * @param x the value to convert to an unsigned {@code int} * @return the argument converted to {@code int} by an unsigned * conversion * @since 1.8 */ public static int toUnsignedInt(short x) { return ((int) x) & 0xffff; } /** * Converts the argument to a {@code long} by an unsigned * conversion. In an unsigned conversion to a {@code long}, the * high-order 48 bits of the {@code long} are zero and the * low-order 16 bits are equal to the bits of the {@code short} argument. * * Consequently, zero and positive {@code short} values are mapped * to a numerically equal {@code long} value and negative {@code * short} values are mapped to a {@code long} value equal to the * input plus 2<sup>16</sup>. * * @param x the value to convert to an unsigned {@code long} * @return the argument converted to {@code long} by an unsigned * conversion * @since 1.8 */ public static long toUnsignedLong(short x) { return ((long) x) & 0xffffL; } /** use serialVersionUID from JDK 1.1. for interoperability */ private static final long serialVersionUID = 7515723908773894738L; }