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1878 lines (1766 loc) · 72.1 KB
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/*
* Copyright (c) 1994, 2021, 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 java.lang.annotation.Native;
import java.lang.invoke.MethodHandles;
import java.lang.constant.Constable;
import java.lang.constant.ConstantDesc;
import java.util.Objects;
import java.util.Optional;
import jdk.internal.misc.CDS;
import jdk.internal.misc.VM;
import jdk.internal.vm.annotation.IntrinsicCandidate;
import static java.lang.String.COMPACT_STRINGS;
import static java.lang.String.LATIN1;
import static java.lang.String.UTF16;
/**
* The {@code Integer} class wraps a value of the primitive type
* {@code int} in an object. An object of type {@code Integer}
* contains a single field whose type is {@code int}.
*
* <p>In addition, this class provides several methods for converting
* an {@code int} to a {@code String} and a {@code String} to an
* {@code int}, as well as other constants and methods useful when
* dealing with an {@code int}.
*
* <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
* class; programmers should treat instances that are
* {@linkplain #equals(Object) equal} as interchangeable and should not
* use instances for synchronization, or unpredictable behavior may
* occur. For example, in a future release, synchronization may fail.
*
* <p>Implementation note: The implementations of the "bit twiddling"
* methods (such as {@link #highestOneBit(int) highestOneBit} and
* {@link #numberOfTrailingZeros(int) numberOfTrailingZeros}) are
* based on material from Henry S. Warren, Jr.'s <i>Hacker's
* Delight</i>, (Addison Wesley, 2002).
*
* @author Lee Boynton
* @author Arthur van Hoff
* @author Josh Bloch
* @author Joseph D. Darcy
* @since 1.0
*/
@jdk.internal.ValueBased
public final class Integer extends Number
implements Comparable<Integer>, Constable, ConstantDesc {
/**
* A constant holding the minimum value an {@code int} can
* have, -2<sup>31</sup>.
*/
@Native public static final int MIN_VALUE = 0x80000000;
/**
* A constant holding the maximum value an {@code int} can
* have, 2<sup>31</sup>-1.
*/
@Native public static final int MAX_VALUE = 0x7fffffff;
/**
* The {@code Class} instance representing the primitive type
* {@code int}.
*
* @since 1.1
*/
@SuppressWarnings("unchecked")
public static final Class<Integer> TYPE = (Class<Integer>) Class.getPrimitiveClass("int");
/**
* All possible chars for representing a number as a String
*/
static final char[] digits = {
'0' , '1' , '2' , '3' , '4' , '5' ,
'6' , '7' , '8' , '9' , 'a' , 'b' ,
'c' , 'd' , 'e' , 'f' , 'g' , 'h' ,
'i' , 'j' , 'k' , 'l' , 'm' , 'n' ,
'o' , 'p' , 'q' , 'r' , 's' , 't' ,
'u' , 'v' , 'w' , 'x' , 'y' , 'z'
};
/**
* Returns a string representation of the first argument in the
* radix specified by the second argument.
*
* <p>If the radix is smaller than {@code Character.MIN_RADIX}
* or larger than {@code Character.MAX_RADIX}, then the radix
* {@code 10} is used instead.
*
* <p>If the first argument is negative, the first element of the
* result is the ASCII minus character {@code '-'}
* ({@code '\u005Cu002D'}). If the first argument is not
* negative, no sign character appears in the result.
*
* <p>The remaining characters of the result represent the magnitude
* of the first argument. If the magnitude is zero, it is
* represented by a single zero character {@code '0'}
* ({@code '\u005Cu0030'}); otherwise, the first character of
* the representation of the magnitude will not be the zero
* character. The following ASCII characters are used as digits:
*
* <blockquote>
* {@code 0123456789abcdefghijklmnopqrstuvwxyz}
* </blockquote>
*
* These are {@code '\u005Cu0030'} through
* {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
* {@code '\u005Cu007A'}. If {@code radix} is
* <var>N</var>, then the first <var>N</var> of these characters
* are used as radix-<var>N</var> digits in the order shown. Thus,
* the digits for hexadecimal (radix 16) are
* {@code 0123456789abcdef}. If uppercase letters are
* desired, the {@link java.lang.String#toUpperCase()} method may
* be called on the result:
*
* <blockquote>
* {@code Integer.toString(n, 16).toUpperCase()}
* </blockquote>
*
* @param i an integer to be converted to a string.
* @param radix the radix to use in the string representation.
* @return a string representation of the argument in the specified radix.
* @see java.lang.Character#MAX_RADIX
* @see java.lang.Character#MIN_RADIX
*/
public static String toString(int i, int radix) {
if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
radix = 10;
/* Use the faster version */
if (radix == 10) {
return toString(i);
}
if (COMPACT_STRINGS) {
byte[] buf = new byte[33];
boolean negative = (i < 0);
int charPos = 32;
if (!negative) {
i = -i;
}
while (i <= -radix) {
buf[charPos--] = (byte)digits[-(i % radix)];
i = i / radix;
}
buf[charPos] = (byte)digits[-i];
if (negative) {
buf[--charPos] = '-';
}
return StringLatin1.newString(buf, charPos, (33 - charPos));
}
return toStringUTF16(i, radix);
}
private static String toStringUTF16(int i, int radix) {
byte[] buf = new byte[33 * 2];
boolean negative = (i < 0);
int charPos = 32;
if (!negative) {
i = -i;
}
while (i <= -radix) {
StringUTF16.putChar(buf, charPos--, digits[-(i % radix)]);
i = i / radix;
}
StringUTF16.putChar(buf, charPos, digits[-i]);
if (negative) {
StringUTF16.putChar(buf, --charPos, '-');
}
return StringUTF16.newString(buf, charPos, (33 - charPos));
}
/**
* Returns a string representation of the first argument as an
* unsigned integer value in the radix specified by the second
* argument.
*
* <p>If the radix is smaller than {@code Character.MIN_RADIX}
* or larger than {@code Character.MAX_RADIX}, then the radix
* {@code 10} is used instead.
*
* <p>Note that since the first argument is treated as an unsigned
* value, no leading sign character is printed.
*
* <p>If the magnitude is zero, it is represented by a single zero
* character {@code '0'} ({@code '\u005Cu0030'}); otherwise,
* the first character of the representation of the magnitude will
* not be the zero character.
*
* <p>The behavior of radixes and the characters used as digits
* are the same as {@link #toString(int, int) toString}.
*
* @param i an integer to be converted to an unsigned string.
* @param radix the radix to use in the string representation.
* @return an unsigned string representation of the argument in the specified radix.
* @see #toString(int, int)
* @since 1.8
*/
public static String toUnsignedString(int i, int radix) {
return Long.toUnsignedString(toUnsignedLong(i), radix);
}
/**
* Returns a string representation of the integer argument as an
* unsigned integer in base 16.
*
* <p>The unsigned integer value is the argument plus 2<sup>32</sup>
* if the argument is negative; otherwise, it is equal to the
* argument. This value is converted to a string of ASCII digits
* in hexadecimal (base 16) with no extra leading
* {@code 0}s.
*
* <p>The value of the argument can be recovered from the returned
* string {@code s} by calling {@link
* Integer#parseUnsignedInt(String, int)
* Integer.parseUnsignedInt(s, 16)}.
*
* <p>If the unsigned magnitude is zero, it is represented by a
* single zero character {@code '0'} ({@code '\u005Cu0030'});
* otherwise, the first character of the representation of the
* unsigned magnitude will not be the zero character. The
* following characters are used as hexadecimal digits:
*
* <blockquote>
* {@code 0123456789abcdef}
* </blockquote>
*
* These are the characters {@code '\u005Cu0030'} through
* {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
* {@code '\u005Cu0066'}. If uppercase letters are
* desired, the {@link java.lang.String#toUpperCase()} method may
* be called on the result:
*
* <blockquote>
* {@code Integer.toHexString(n).toUpperCase()}
* </blockquote>
*
* @apiNote
* The {@link java.util.HexFormat} class provides formatting and parsing
* of byte arrays and primitives to return a string or adding to an {@link Appendable}.
* {@code HexFormat} formats and parses uppercase or lowercase hexadecimal characters,
* with leading zeros and for byte arrays includes for each byte
* a delimiter, prefix, and suffix.
*
* @param i an integer to be converted to a string.
* @return the string representation of the unsigned integer value
* represented by the argument in hexadecimal (base 16).
* @see java.util.HexFormat
* @see #parseUnsignedInt(String, int)
* @see #toUnsignedString(int, int)
* @since 1.0.2
*/
public static String toHexString(int i) {
return toUnsignedString0(i, 4);
}
/**
* Returns a string representation of the integer argument as an
* unsigned integer in base 8.
*
* <p>The unsigned integer value is the argument plus 2<sup>32</sup>
* if the argument is negative; otherwise, it is equal to the
* argument. This value is converted to a string of ASCII digits
* in octal (base 8) with no extra leading {@code 0}s.
*
* <p>The value of the argument can be recovered from the returned
* string {@code s} by calling {@link
* Integer#parseUnsignedInt(String, int)
* Integer.parseUnsignedInt(s, 8)}.
*
* <p>If the unsigned magnitude is zero, it is represented by a
* single zero character {@code '0'} ({@code '\u005Cu0030'});
* otherwise, the first character of the representation of the
* unsigned magnitude will not be the zero character. The
* following characters are used as octal digits:
*
* <blockquote>
* {@code 01234567}
* </blockquote>
*
* These are the characters {@code '\u005Cu0030'} through
* {@code '\u005Cu0037'}.
*
* @param i an integer to be converted to a string.
* @return the string representation of the unsigned integer value
* represented by the argument in octal (base 8).
* @see #parseUnsignedInt(String, int)
* @see #toUnsignedString(int, int)
* @since 1.0.2
*/
public static String toOctalString(int i) {
return toUnsignedString0(i, 3);
}
/**
* Returns a string representation of the integer argument as an
* unsigned integer in base 2.
*
* <p>The unsigned integer value is the argument plus 2<sup>32</sup>
* if the argument is negative; otherwise it is equal to the
* argument. This value is converted to a string of ASCII digits
* in binary (base 2) with no extra leading {@code 0}s.
*
* <p>The value of the argument can be recovered from the returned
* string {@code s} by calling {@link
* Integer#parseUnsignedInt(String, int)
* Integer.parseUnsignedInt(s, 2)}.
*
* <p>If the unsigned magnitude is zero, it is represented by a
* single zero character {@code '0'} ({@code '\u005Cu0030'});
* otherwise, the first character of the representation of the
* unsigned magnitude will not be the zero character. The
* characters {@code '0'} ({@code '\u005Cu0030'}) and {@code
* '1'} ({@code '\u005Cu0031'}) are used as binary digits.
*
* @param i an integer to be converted to a string.
* @return the string representation of the unsigned integer value
* represented by the argument in binary (base 2).
* @see #parseUnsignedInt(String, int)
* @see #toUnsignedString(int, int)
* @since 1.0.2
*/
public static String toBinaryString(int i) {
return toUnsignedString0(i, 1);
}
/**
* Convert the integer to an unsigned number.
*/
private static String toUnsignedString0(int val, int shift) {
// assert shift > 0 && shift <=5 : "Illegal shift value";
int mag = Integer.SIZE - Integer.numberOfLeadingZeros(val);
int chars = Math.max(((mag + (shift - 1)) / shift), 1);
if (COMPACT_STRINGS) {
byte[] buf = new byte[chars];
formatUnsignedInt(val, shift, buf, chars);
return new String(buf, LATIN1);
} else {
byte[] buf = new byte[chars * 2];
formatUnsignedIntUTF16(val, shift, buf, chars);
return new String(buf, UTF16);
}
}
/**
* Format an {@code int} (treated as unsigned) into a byte buffer (LATIN1 version). If
* {@code len} exceeds the formatted ASCII representation of {@code val},
* {@code buf} will be padded with leading zeroes.
*
* @param val the unsigned int to format
* @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
* @param buf the byte buffer to write to
* @param len the number of characters to write
*/
private static void formatUnsignedInt(int val, int shift, byte[] buf, int len) {
int charPos = len;
int radix = 1 << shift;
int mask = radix - 1;
do {
buf[--charPos] = (byte)Integer.digits[val & mask];
val >>>= shift;
} while (charPos > 0);
}
/**
* Format an {@code int} (treated as unsigned) into a byte buffer (UTF16 version). If
* {@code len} exceeds the formatted ASCII representation of {@code val},
* {@code buf} will be padded with leading zeroes.
*
* @param val the unsigned int to format
* @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
* @param buf the byte buffer to write to
* @param len the number of characters to write
*/
private static void formatUnsignedIntUTF16(int val, int shift, byte[] buf, int len) {
int charPos = len;
int radix = 1 << shift;
int mask = radix - 1;
do {
StringUTF16.putChar(buf, --charPos, Integer.digits[val & mask]);
val >>>= shift;
} while (charPos > 0);
}
static final byte[] DigitTens = {
'0', '0', '0', '0', '0', '0', '0', '0', '0', '0',
'1', '1', '1', '1', '1', '1', '1', '1', '1', '1',
'2', '2', '2', '2', '2', '2', '2', '2', '2', '2',
'3', '3', '3', '3', '3', '3', '3', '3', '3', '3',
'4', '4', '4', '4', '4', '4', '4', '4', '4', '4',
'5', '5', '5', '5', '5', '5', '5', '5', '5', '5',
'6', '6', '6', '6', '6', '6', '6', '6', '6', '6',
'7', '7', '7', '7', '7', '7', '7', '7', '7', '7',
'8', '8', '8', '8', '8', '8', '8', '8', '8', '8',
'9', '9', '9', '9', '9', '9', '9', '9', '9', '9',
} ;
static final byte[] DigitOnes = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
} ;
/**
* Returns a {@code String} object representing the
* specified integer. The argument is converted to signed decimal
* representation and returned as a string, exactly as if the
* argument and radix 10 were given as arguments to the {@link
* #toString(int, int)} method.
*
* @param i an integer to be converted.
* @return a string representation of the argument in base 10.
*/
@IntrinsicCandidate
public static String toString(int i) {
int size = stringSize(i);
if (COMPACT_STRINGS) {
byte[] buf = new byte[size];
getChars(i, size, buf);
return new String(buf, LATIN1);
} else {
byte[] buf = new byte[size * 2];
StringUTF16.getChars(i, size, buf);
return new String(buf, UTF16);
}
}
/**
* Returns a string representation of the argument as an unsigned
* decimal value.
*
* The argument is converted to unsigned decimal representation
* and returned as a string exactly as if the argument and radix
* 10 were given as arguments to the {@link #toUnsignedString(int,
* int)} method.
*
* @param i an integer to be converted to an unsigned string.
* @return an unsigned string representation of the argument.
* @see #toUnsignedString(int, int)
* @since 1.8
*/
public static String toUnsignedString(int i) {
return Long.toString(toUnsignedLong(i));
}
/**
* Places characters representing the integer i into the
* character array buf. The characters are placed into
* the buffer backwards starting with the least significant
* digit at the specified index (exclusive), and working
* backwards from there.
*
* @implNote This method converts positive inputs into negative
* values, to cover the Integer.MIN_VALUE case. Converting otherwise
* (negative to positive) will expose -Integer.MIN_VALUE that overflows
* integer.
*
* @param i value to convert
* @param index next index, after the least significant digit
* @param buf target buffer, Latin1-encoded
* @return index of the most significant digit or minus sign, if present
*/
static int getChars(int i, int index, byte[] buf) {
int q, r;
int charPos = index;
boolean negative = i < 0;
if (!negative) {
i = -i;
}
// Generate two digits per iteration
while (i <= -100) {
q = i / 100;
r = (q * 100) - i;
i = q;
buf[--charPos] = DigitOnes[r];
buf[--charPos] = DigitTens[r];
}
// We know there are at most two digits left at this point.
q = i / 10;
r = (q * 10) - i;
buf[--charPos] = (byte)('0' + r);
// Whatever left is the remaining digit.
if (q < 0) {
buf[--charPos] = (byte)('0' - q);
}
if (negative) {
buf[--charPos] = (byte)'-';
}
return charPos;
}
// Left here for compatibility reasons, see JDK-8143900.
static final int [] sizeTable = { 9, 99, 999, 9999, 99999, 999999, 9999999,
99999999, 999999999, Integer.MAX_VALUE };
/**
* Returns the string representation size for a given int value.
*
* @param x int value
* @return string size
*
* @implNote There are other ways to compute this: e.g. binary search,
* but values are biased heavily towards zero, and therefore linear search
* wins. The iteration results are also routinely inlined in the generated
* code after loop unrolling.
*/
static int stringSize(int x) {
int d = 1;
if (x >= 0) {
d = 0;
x = -x;
}
int p = -10;
for (int i = 1; i < 10; i++) {
if (x > p)
return i + d;
p = 10 * p;
}
return 10 + d;
}
/**
* Parses the string argument as a signed integer 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 integer 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 int}.
* </ul>
*
* <p>Examples:
* <blockquote><pre>
* parseInt("0", 10) returns 0
* parseInt("473", 10) returns 473
* parseInt("+42", 10) returns 42
* parseInt("-0", 10) returns 0
* parseInt("-FF", 16) returns -255
* parseInt("1100110", 2) returns 102
* parseInt("2147483647", 10) returns 2147483647
* parseInt("-2147483648", 10) returns -2147483648
* parseInt("2147483648", 10) throws a NumberFormatException
* parseInt("99", 8) throws a NumberFormatException
* parseInt("Kona", 10) throws a NumberFormatException
* parseInt("Kona", 27) returns 411787
* </pre></blockquote>
*
* @param s the {@code String} containing the integer
* representation to be parsed
* @param radix the radix to be used while parsing {@code s}.
* @return the integer represented by the string argument in the
* specified radix.
* @throws NumberFormatException if the {@code String}
* does not contain a parsable {@code int}.
*/
public static int parseInt(String s, int radix)
throws NumberFormatException
{
/*
* WARNING: This method may be invoked early during VM initialization
* before IntegerCache is initialized. Care must be taken to not use
* the valueOf method.
*/
if (s == null) {
throw new NumberFormatException("Cannot parse null string");
}
if (radix < Character.MIN_RADIX) {
throw new NumberFormatException("radix " + radix +
" less than Character.MIN_RADIX");
}
if (radix > Character.MAX_RADIX) {
throw new NumberFormatException("radix " + radix +
" greater than Character.MAX_RADIX");
}
boolean negative = false;
int i = 0, len = s.length();
int limit = -Integer.MAX_VALUE;
if (len > 0) {
char firstChar = s.charAt(0);
if (firstChar < '0') { // Possible leading "+" or "-"
if (firstChar == '-') {
negative = true;
limit = Integer.MIN_VALUE;
} else if (firstChar != '+') {
throw NumberFormatException.forInputString(s, radix);
}
if (len == 1) { // Cannot have lone "+" or "-"
throw NumberFormatException.forInputString(s, radix);
}
i++;
}
int multmin = limit / radix;
int result = 0;
while (i < len) {
// Accumulating negatively avoids surprises near MAX_VALUE
int digit = Character.digit(s.charAt(i++), radix);
if (digit < 0 || result < multmin) {
throw NumberFormatException.forInputString(s, radix);
}
result *= radix;
if (result < limit + digit) {
throw NumberFormatException.forInputString(s, radix);
}
result -= digit;
}
return negative ? result : -result;
} else {
throw NumberFormatException.forInputString(s, radix);
}
}
/**
* Parses the {@link CharSequence} argument as a signed {@code int} in the
* specified {@code radix}, beginning at the specified {@code beginIndex}
* and extending to {@code endIndex - 1}.
*
* <p>The method does not take steps to guard against the
* {@code CharSequence} being mutated while parsing.
*
* @param s the {@code CharSequence} containing the {@code int}
* representation to be parsed
* @param beginIndex the beginning index, inclusive.
* @param endIndex the ending index, exclusive.
* @param radix the radix to be used while parsing {@code s}.
* @return the signed {@code int} represented by the subsequence in
* the specified radix.
* @throws NullPointerException if {@code s} is null.
* @throws IndexOutOfBoundsException if {@code beginIndex} is
* negative, or if {@code beginIndex} is greater than
* {@code endIndex} or if {@code endIndex} is greater than
* {@code s.length()}.
* @throws NumberFormatException if the {@code CharSequence} does not
* contain a parsable {@code int} in the specified
* {@code radix}, or if {@code radix} is either smaller than
* {@link java.lang.Character#MIN_RADIX} or larger than
* {@link java.lang.Character#MAX_RADIX}.
* @since 9
*/
public static int parseInt(CharSequence s, int beginIndex, int endIndex, int radix)
throws NumberFormatException {
Objects.requireNonNull(s);
if (beginIndex < 0 || beginIndex > endIndex || endIndex > s.length()) {
throw new IndexOutOfBoundsException();
}
if (radix < Character.MIN_RADIX) {
throw new NumberFormatException("radix " + radix +
" less than Character.MIN_RADIX");
}
if (radix > Character.MAX_RADIX) {
throw new NumberFormatException("radix " + radix +
" greater than Character.MAX_RADIX");
}
boolean negative = false;
int i = beginIndex;
int limit = -Integer.MAX_VALUE;
if (i < endIndex) {
char firstChar = s.charAt(i);
if (firstChar < '0') { // Possible leading "+" or "-"
if (firstChar == '-') {
negative = true;
limit = Integer.MIN_VALUE;
} else if (firstChar != '+') {
throw NumberFormatException.forCharSequence(s, beginIndex,
endIndex, i);
}
i++;
if (i == endIndex) { // Cannot have lone "+" or "-"
throw NumberFormatException.forCharSequence(s, beginIndex,
endIndex, i);
}
}
int multmin = limit / radix;
int result = 0;
while (i < endIndex) {
// Accumulating negatively avoids surprises near MAX_VALUE
int digit = Character.digit(s.charAt(i), radix);
if (digit < 0 || result < multmin) {
throw NumberFormatException.forCharSequence(s, beginIndex,
endIndex, i);
}
result *= radix;
if (result < limit + digit) {
throw NumberFormatException.forCharSequence(s, beginIndex,
endIndex, i);
}
i++;
result -= digit;
}
return negative ? result : -result;
} else {
throw NumberFormatException.forInputString("", radix);
}
}
/**
* Parses the string argument as a signed decimal integer. 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 integer value is
* returned, exactly as if the argument and the radix 10 were
* given as arguments to the {@link #parseInt(java.lang.String,
* int)} method.
*
* @param s a {@code String} containing the {@code int}
* representation to be parsed
* @return the integer value represented by the argument in decimal.
* @throws NumberFormatException if the string does not contain a
* parsable integer.
*/
public static int parseInt(String s) throws NumberFormatException {
return parseInt(s,10);
}
/**
* Parses the string argument as an unsigned integer in the radix
* specified by the second argument. An unsigned integer maps the
* values usually associated with negative numbers to positive
* numbers larger than {@code MAX_VALUE}.
*
* 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 plus
* sign {@code '+'} ({@code '\u005Cu002B'}). The resulting
* integer 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 plus sign
* {@code '+'} ({@code '\u005Cu002B'}) provided that the
* string is longer than length 1.
*
* <li>The value represented by the string is larger than the
* largest unsigned {@code int}, 2<sup>32</sup>-1.
*
* </ul>
*
*
* @param s the {@code String} containing the unsigned integer
* representation to be parsed
* @param radix the radix to be used while parsing {@code s}.
* @return the integer represented by the string argument in the
* specified radix.
* @throws NumberFormatException if the {@code String}
* does not contain a parsable {@code int}.
* @since 1.8
*/
public static int parseUnsignedInt(String s, int radix)
throws NumberFormatException {
if (s == null) {
throw new NumberFormatException("Cannot parse null string");
}
int len = s.length();
if (len > 0) {
char firstChar = s.charAt(0);
if (firstChar == '-') {
throw new
NumberFormatException(String.format("Illegal leading minus sign " +
"on unsigned string %s.", s));
} else {
if (len <= 5 || // Integer.MAX_VALUE in Character.MAX_RADIX is 6 digits
(radix == 10 && len <= 9) ) { // Integer.MAX_VALUE in base 10 is 10 digits
return parseInt(s, radix);
} else {
long ell = Long.parseLong(s, radix);
if ((ell & 0xffff_ffff_0000_0000L) == 0) {
return (int) ell;
} else {
throw new
NumberFormatException(String.format("String value %s exceeds " +
"range of unsigned int.", s));
}
}
}
} else {
throw NumberFormatException.forInputString(s, radix);
}
}
/**
* Parses the {@link CharSequence} argument as an unsigned {@code int} in
* the specified {@code radix}, beginning at the specified
* {@code beginIndex} and extending to {@code endIndex - 1}.
*
* <p>The method does not take steps to guard against the
* {@code CharSequence} being mutated while parsing.
*
* @param s the {@code CharSequence} containing the unsigned
* {@code int} representation to be parsed
* @param beginIndex the beginning index, inclusive.
* @param endIndex the ending index, exclusive.
* @param radix the radix to be used while parsing {@code s}.
* @return the unsigned {@code int} represented by the subsequence in
* the specified radix.
* @throws NullPointerException if {@code s} is null.
* @throws IndexOutOfBoundsException if {@code beginIndex} is
* negative, or if {@code beginIndex} is greater than
* {@code endIndex} or if {@code endIndex} is greater than
* {@code s.length()}.
* @throws NumberFormatException if the {@code CharSequence} does not
* contain a parsable unsigned {@code int} in the specified
* {@code radix}, or if {@code radix} is either smaller than
* {@link java.lang.Character#MIN_RADIX} or larger than
* {@link java.lang.Character#MAX_RADIX}.
* @since 9
*/
public static int parseUnsignedInt(CharSequence s, int beginIndex, int endIndex, int radix)
throws NumberFormatException {
Objects.requireNonNull(s);
if (beginIndex < 0 || beginIndex > endIndex || endIndex > s.length()) {
throw new IndexOutOfBoundsException();
}
int start = beginIndex, len = endIndex - beginIndex;
if (len > 0) {
char firstChar = s.charAt(start);
if (firstChar == '-') {
throw new
NumberFormatException(String.format("Illegal leading minus sign " +
"on unsigned string %s.", s));
} else {
if (len <= 5 || // Integer.MAX_VALUE in Character.MAX_RADIX is 6 digits
(radix == 10 && len <= 9)) { // Integer.MAX_VALUE in base 10 is 10 digits
return parseInt(s, start, start + len, radix);
} else {
long ell = Long.parseLong(s, start, start + len, radix);
if ((ell & 0xffff_ffff_0000_0000L) == 0) {
return (int) ell;
} else {
throw new
NumberFormatException(String.format("String value %s exceeds " +
"range of unsigned int.", s));
}
}
}
} else {
throw new NumberFormatException("");
}
}
/**
* Parses the string argument as an unsigned decimal integer. The
* characters in the string must all be decimal digits, except
* that the first character may be an ASCII plus sign {@code
* '+'} ({@code '\u005Cu002B'}). The resulting integer value
* is returned, exactly as if the argument and the radix 10 were
* given as arguments to the {@link
* #parseUnsignedInt(java.lang.String, int)} method.
*
* @param s a {@code String} containing the unsigned {@code int}
* representation to be parsed
* @return the unsigned integer value represented by the argument in decimal.
* @throws NumberFormatException if the string does not contain a
* parsable unsigned integer.
* @since 1.8
*/
public static int parseUnsignedInt(String s) throws NumberFormatException {
return parseUnsignedInt(s, 10);
}
/**
* Returns an {@code Integer} 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 integer in the radix
* specified by the second argument, exactly as if the arguments
* were given to the {@link #parseInt(java.lang.String, int)}
* method. The result is an {@code Integer} object that
* represents the integer value specified by the string.
*
* <p>In other words, this method returns an {@code Integer}
* object equal to the value of:
*
* <blockquote>
* {@code new Integer(Integer.parseInt(s, radix))}
* </blockquote>
*
* @param s the string to be parsed.
* @param radix the radix to be used in interpreting {@code s}
* @return an {@code Integer} 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 int}.
*/
public static Integer valueOf(String s, int radix) throws NumberFormatException {
return Integer.valueOf(parseInt(s,radix));
}
/**
* Returns an {@code Integer} object holding the
* value of the specified {@code String}. The argument is
* interpreted as representing a signed decimal integer, exactly
* as if the argument were given to the {@link
* #parseInt(java.lang.String)} method. The result is an
* {@code Integer} object that represents the integer value
* specified by the string.
*
* <p>In other words, this method returns an {@code Integer}
* object equal to the value of:
*
* <blockquote>
* {@code new Integer(Integer.parseInt(s))}
* </blockquote>
*
* @param s the string to be parsed.
* @return an {@code Integer} object holding the value
* represented by the string argument.
* @throws NumberFormatException if the string cannot be parsed
* as an integer.
*/
public static Integer valueOf(String s) throws NumberFormatException {
return Integer.valueOf(parseInt(s, 10));
}