JDK Long源码
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JDK Long源码
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// final修飾符
public final class Long extends Number implements Comparable<Long> {/*** A constant holding the minimum value a {@code long} can* have, -2<sup>63</sup>.*/
// 最小值-負值@Native public static final long MIN_VALUE = 0x8000000000000000L;/*** A constant holding the maximum value a {@code long} can* have, 2<sup>63</sup>-1.*/
// 最大值-有符號@Native public static final long MAX_VALUE = 0x7fffffffffffffffL;/*** The {@code Class} instance representing the primitive type* {@code long}.** @since JDK1.1*/@SuppressWarnings("unchecked")
// class public static final Class<Long> TYPE = (Class<Long>) Class.getPrimitiveClass("long");/*** 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 sign {@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 Long.toString(n, 16).toUpperCase()}* </blockquote>** @param i a {@code long} 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*/
// radix 基數public static String toString(long i, int radix) {if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)radix = 10;if (radix == 10)return toString(i);char[] buf = new char[65];int charPos = 64;boolean negative = (i < 0);if (!negative) {i = -i;}while (i <= -radix) {buf[charPos--] = Integer.digits[(int)(-(i % radix))];i = i / radix;}buf[charPos] = Integer.digits[(int)(-i)];if (negative) {buf[--charPos] = '-';}return new String(buf, charPos, (65 - 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(long, 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(long, int)* @since 1.8*/public static String toUnsignedString(long i, int radix) {if (i >= 0)return toString(i, radix);else {switch (radix) {case 2:return toBinaryString(i);case 4:return toUnsignedString0(i, 2);case 8:return toOctalString(i);case 10:/** We can get the effect of an unsigned division by 10* on a long value by first shifting right, yielding a* positive value, and then dividing by 5. This* allows the last digit and preceding digits to be* isolated more quickly than by an initial conversion* to BigInteger.*/long quot = (i >>> 1) / 5;long rem = i - quot * 10;return toString(quot) + rem;case 16:return toHexString(i);case 32:return toUnsignedString0(i, 5);default:return toUnsignedBigInteger(i).toString(radix);}}}/*** Return a BigInteger equal to the unsigned value of the* argument.*/private static BigInteger toUnsignedBigInteger(long i) {if (i >= 0L)return BigInteger.valueOf(i);else {int upper = (int) (i >>> 32);int lower = (int) i;// return (upper << 32) + lowerreturn (BigInteger.valueOf(Integer.toUnsignedLong(upper))).shiftLeft(32).add(BigInteger.valueOf(Integer.toUnsignedLong(lower)));}}/*** Returns a string representation of the {@code long}* argument as an unsigned integer in base 16.** <p>The unsigned {@code long} value is the argument plus* 2<sup>64</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* Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(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 Long.toHexString(n).toUpperCase()}* </blockquote>** @param i a {@code long} to be converted to a string.* @return the string representation of the unsigned {@code long}* value represented by the argument in hexadecimal* (base 16).* @see #parseUnsignedLong(String, int)* @see #toUnsignedString(long, int)* @since JDK 1.0.2*/public static String toHexString(long i) {return toUnsignedString0(i, 4);}/*** Returns a string representation of the {@code long}* argument as an unsigned integer in base 8.** <p>The unsigned {@code long} value is the argument plus* 2<sup>64</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* Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(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 a {@code long} to be converted to a string.* @return the string representation of the unsigned {@code long}* value represented by the argument in octal (base 8).* @see #parseUnsignedLong(String, int)* @see #toUnsignedString(long, int)* @since JDK 1.0.2*/public static String toOctalString(long i) {return toUnsignedString0(i, 3);}/*** Returns a string representation of the {@code long}* argument as an unsigned integer in base 2.** <p>The unsigned {@code long} value is the argument plus* 2<sup>64</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* Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(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 a {@code long} to be converted to a string.* @return the string representation of the unsigned {@code long}* value represented by the argument in binary (base 2).* @see #parseUnsignedLong(String, int)* @see #toUnsignedString(long, int)* @since JDK 1.0.2*/public static String toBinaryString(long i) {return toUnsignedString0(i, 1);}/*** Format a long (treated as unsigned) into a String.* @param val the value to format* @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)*/static String toUnsignedString0(long val, int shift) {// assert shift > 0 && shift <=5 : "Illegal shift value";int mag = Long.SIZE - Long.numberOfLeadingZeros(val);int chars = Math.max(((mag + (shift - 1)) / shift), 1);char[] buf = new char[chars];formatUnsignedLong(val, shift, buf, 0, chars);return new String(buf, true);}/*** Format a long (treated as unsigned) into a character buffer.* @param val the unsigned long to format* @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)* @param buf the character buffer to write to* @param offset the offset in the destination buffer to start at* @param len the number of characters to write* @return the lowest character location used*/static int formatUnsignedLong(long val, int shift, char[] buf, int offset, int len) {int charPos = len;int radix = 1 << shift;int mask = radix - 1;do {buf[offset + --charPos] = Integer.digits[((int) val) & mask];val >>>= shift;} while (val != 0 && charPos > 0);return charPos;}/*** Returns a {@code String} object representing the specified* {@code long}. The argument is converted to signed decimal* representation and returned as a string, exactly as if the* argument and the radix 10 were given as arguments to the {@link* #toString(long, int)} method.** @param i a {@code long} to be converted.* @return a string representation of the argument in base 10.*/public static String toString(long i) {if (i == Long.MIN_VALUE)return "-9223372036854775808";int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);char[] buf = new char[size];getChars(i, size, buf);return new String(buf, true);}/*** 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(long,* int)} method.** @param i an integer to be converted to an unsigned string.* @return an unsigned string representation of the argument.* @see #toUnsignedString(long, int)* @since 1.8*/public static String toUnsignedString(long i) {return toUnsignedString(i, 10);}/*** 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.** Will fail if i == Long.MIN_VALUE*/static void getChars(long i, int index, char[] buf) {long q;int r;int charPos = index;char sign = 0;if (i < 0) {sign = '-';i = -i;}// Get 2 digits/iteration using longs until quotient fits into an intwhile (i > Integer.MAX_VALUE) {q = i / 100;// really: r = i - (q * 100);r = (int)(i - ((q << 6) + (q << 5) + (q << 2)));i = q;buf[--charPos] = Integer.DigitOnes[r];buf[--charPos] = Integer.DigitTens[r];}// Get 2 digits/iteration using intsint q2;int i2 = (int)i;while (i2 >= 65536) {q2 = i2 / 100;// really: r = i2 - (q * 100);r = i2 - ((q2 << 6) + (q2 << 5) + (q2 << 2));i2 = q2;buf[--charPos] = Integer.DigitOnes[r];buf[--charPos] = Integer.DigitTens[r];}// Fall thru to fast mode for smaller numbers// assert(i2 <= 65536, i2);for (;;) {q2 = (i2 * 52429) >>> (16+3);r = i2 - ((q2 << 3) + (q2 << 1)); // r = i2-(q2*10) ...buf[--charPos] = Integer.digits[r];i2 = q2;if (i2 == 0) break;}if (sign != 0) {buf[--charPos] = sign;}}// Requires positive xstatic int stringSize(long x) {long p = 10;for (int i=1; i<19; i++) {if (x < p)return i;p = 10*p;}return 19;}/*** Parses the string argument as a signed {@code long} 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 long} value is returned.** <p>Note that neither the character {@code L}* ({@code '\u005Cu004C'}) nor {@code l}* ({@code '\u005Cu006C'}) is permitted to appear at the end* of the string as a type indicator, as would be permitted in* Java programming language source code - except that either* {@code L} or {@code l} may appear as a digit for a* radix greater than or equal to 22.** <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 {@code 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 long}.* </ul>** <p>Examples:* <blockquote><pre>* parseLong("0", 10) returns 0L* parseLong("473", 10) returns 473L* parseLong("+42", 10) returns 42L* parseLong("-0", 10) returns 0L* parseLong("-FF", 16) returns -255L* parseLong("1100110", 2) returns 102L* parseLong("99", 8) throws a NumberFormatException* parseLong("Hazelnut", 10) throws a NumberFormatException* parseLong("Hazelnut", 36) returns 1356099454469L* </pre></blockquote>** @param s the {@code String} containing the* {@code long} representation to be parsed.* @param radix the radix to be used while parsing {@code s}.* @return the {@code long} represented by the string argument in* the specified radix.* @throws NumberFormatException if the string does not contain a* parsable {@code long}.*/public static long parseLong(String s, int radix)throws NumberFormatException{if (s == null) {throw new NumberFormatException("null");}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");}long result = 0;boolean negative = false;int i = 0, len = s.length();long limit = -Long.MAX_VALUE;long multmin;int digit;if (len > 0) {char firstChar = s.charAt(0);if (firstChar < '0') { // Possible leading "+" or "-"if (firstChar == '-') {negative = true;limit = Long.MIN_VALUE;} else if (firstChar != '+')throw NumberFormatException.forInputString(s);if (len == 1) // Cannot have lone "+" or "-"throw NumberFormatException.forInputString(s);i++;}multmin = limit / radix;while (i < len) {// Accumulating negatively avoids surprises near MAX_VALUEdigit = Character.digit(s.charAt(i++),radix);if (digit < 0) {throw NumberFormatException.forInputString(s);}if (result < multmin) {throw NumberFormatException.forInputString(s);}result *= radix;if (result < limit + digit) {throw NumberFormatException.forInputString(s);}result -= digit;}} else {throw NumberFormatException.forInputString(s);}return negative ? result : -result;}/*** Parses the string argument as a signed decimal {@code long}.* 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 long} value is* returned, exactly as if the argument and the radix {@code 10}* were given as arguments to the {@link* #parseLong(java.lang.String, int)} method.** <p>Note that neither the character {@code L}* ({@code '\u005Cu004C'}) nor {@code l}* ({@code '\u005Cu006C'}) is permitted to appear at the end* of the string as a type indicator, as would be permitted in* Java programming language source code.** @param s a {@code String} containing the {@code long}* representation to be parsed* @return the {@code long} represented by the argument in* decimal.* @throws NumberFormatException if the string does not contain a* parsable {@code long}.*/public static long parseLong(String s) throws NumberFormatException {return parseLong(s, 10);}/*** Parses the string argument as an unsigned {@code long} 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 long}, 2<sup>64</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 unsigned {@code long} represented by the string* argument in the specified radix.* @throws NumberFormatException if the {@code String}* does not contain a parsable {@code long}.* @since 1.8*/public static long parseUnsignedLong(String s, int radix)throws NumberFormatException {if (s == null) {throw new NumberFormatException("null");}int len = s.length();if (len > 0) {char firstChar = s.charAt(0);if (firstChar == '-') {throw newNumberFormatException(String.format("Illegal leading minus sign " +"on unsigned string %s.", s));} else {if (len <= 12 || // Long.MAX_VALUE in Character.MAX_RADIX is 13 digits(radix == 10 && len <= 18) ) { // Long.MAX_VALUE in base 10 is 19 digitsreturn parseLong(s, radix);}// No need for range checks on len due to testing above.long first = parseLong(s.substring(0, len - 1), radix);int second = Character.digit(s.charAt(len - 1), radix);if (second < 0) {throw new NumberFormatException("Bad digit at end of " + s);}long result = first * radix + second;if (compareUnsigned(result, first) < 0) {/** The maximum unsigned value, (2^64)-1, takes at* most one more digit to represent than the* maximum signed value, (2^63)-1. Therefore,* parsing (len - 1) digits will be appropriately* in-range of the signed parsing. In other* words, if parsing (len -1) digits overflows* signed parsing, parsing len digits will* certainly overflow unsigned parsing.** The compareUnsigned check above catches* situations where an unsigned overflow occurs* incorporating the contribution of the final* digit.*/throw new NumberFormatException(String.format("String value %s exceeds " +"range of unsigned long.", s));}return result;}} else {throw NumberFormatException.forInputString(s);}}/*** Parses the string argument as an unsigned decimal {@code long}. The* characters in the string must all be decimal digits, except* that the first character may be an 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* #parseUnsignedLong(java.lang.String, int)} method.** @param s a {@code String} containing the unsigned {@code long}* representation to be parsed* @return the unsigned {@code long} value represented by the decimal string argument* @throws NumberFormatException if the string does not contain a* parsable unsigned integer.* @since 1.8*/public static long parseUnsignedLong(String s) throws NumberFormatException {return parseUnsignedLong(s, 10);}/*** Returns a {@code Long} 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 long} in the radix specified by the second* argument, exactly as if the arguments were given to the {@link* #parseLong(java.lang.String, int)} method. The result is a* {@code Long} object that represents the {@code long}* value specified by the string.** <p>In other words, this method returns a {@code Long} object equal* to the value of:** <blockquote>* {@code new Long(Long.parseLong(s, radix))}* </blockquote>** @param s the string to be parsed* @param radix the radix to be used in interpreting {@code s}* @return a {@code Long} 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 long}.*/public static Long valueOf(String s, int radix) throws NumberFormatException {return Long.valueOf(parseLong(s, radix));}/*** Returns a {@code Long} object holding the value* of the specified {@code String}. The argument is* interpreted as representing a signed decimal {@code long},* exactly as if the argument were given to the {@link* #parseLong(java.lang.String)} method. The result is a* {@code Long} object that represents the integer value* specified by the string.** <p>In other words, this method returns a {@code Long} object* equal to the value of:** <blockquote>* {@code new Long(Long.parseLong(s))}* </blockquote>** @param s the string to be parsed.* @return a {@code Long} object holding the value* represented by the string argument.* @throws NumberFormatException If the string cannot be parsed* as a {@code long}.*/public static Long valueOf(String s) throws NumberFormatException{return Long.valueOf(parseLong(s, 10));}private static class LongCache {private LongCache(){}static final Long cache[] = new Long[-(-128) + 127 + 1];static {for(int i = 0; i < cache.length; i++)cache[i] = new Long(i - 128);}}/*** Returns a {@code Long} instance representing the specified* {@code long} value.* If a new {@code Long} instance is not required, this method* should generally be used in preference to the constructor* {@link #Long(long)}, as this method is likely to yield* significantly better space and time performance by caching* frequently requested values.** Note that unlike the {@linkplain Integer#valueOf(int)* corresponding method} in the {@code Integer} class, this method* is <em>not</em> required to cache values within a particular* range.** @param l a long value.* @return a {@code Long} instance representing {@code l}.* @since 1.5*/public static Long valueOf(long l) {final int offset = 128;if (l >= -128 && l <= 127) { // will cachereturn LongCache.cache[(int)l + offset];}return new Long(l);}/*** Decodes a {@code String} into a {@code Long}.* 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* Long.parseLong} 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 Long} object holding the {@code long}* value represented by {@code nm}* @throws NumberFormatException if the {@code String} does not* contain a parsable {@code long}.* @see java.lang.Long#parseLong(String, int)* @since 1.2*/public static Long decode(String nm) throws NumberFormatException {int radix = 10;int index = 0;boolean negative = false;Long result;if (nm.length() == 0)throw new NumberFormatException("Zero length string");char firstChar = nm.charAt(0);// Handle sign, if presentif (firstChar == '-') {negative = true;index++;} else if (firstChar == '+')index++;// Handle radix specifier, if presentif (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {index += 2;radix = 16;}else if (nm.startsWith("#", index)) {index ++;radix = 16;}else if (nm.startsWith("0", index) && nm.length() > 1 + index) {index ++;radix = 8;}if (nm.startsWith("-", index) || nm.startsWith("+", index))throw new NumberFormatException("Sign character in wrong position");try {result = Long.valueOf(nm.substring(index), radix);result = negative ? Long.valueOf(-result.longValue()) : result;} catch (NumberFormatException e) {// If number is Long.MIN_VALUE, we'll end up here. The next line// handles this case, and causes any genuine format error to be// rethrown.String constant = negative ? ("-" + nm.substring(index)): nm.substring(index);result = Long.valueOf(constant, radix);}return result;}/*** The value of the {@code Long}.** @serial*/private final long value;/*** Constructs a newly allocated {@code Long} object that* represents the specified {@code long} argument.** @param value the value to be represented by the* {@code Long} object.*/public Long(long value) {this.value = value;}/*** Constructs a newly allocated {@code Long} object that* represents the {@code long} value indicated by the* {@code String} parameter. The string is converted to a* {@code long} value in exactly the manner used by the* {@code parseLong} method for radix 10.** @param s the {@code String} to be converted to a* {@code Long}.* @throws NumberFormatException if the {@code String} does not* contain a parsable {@code long}.* @see java.lang.Long#parseLong(java.lang.String, int)*/public Long(String s) throws NumberFormatException {this.value = parseLong(s, 10);}/*** Returns the value of this {@code Long} as a {@code byte} after* a narrowing primitive conversion.* @jls 5.1.3 Narrowing Primitive Conversions*/public byte byteValue() {return (byte)value;}/*** Returns the value of this {@code Long} as a {@code short} after* a narrowing primitive conversion.* @jls 5.1.3 Narrowing Primitive Conversions*/public short shortValue() {return (short)value;}/*** Returns the value of this {@code Long} as an {@code int} after* a narrowing primitive conversion.* @jls 5.1.3 Narrowing Primitive Conversions*/public int intValue() {return (int)value;}/*** Returns the value of this {@code Long} as a* {@code long} value.*/public long longValue() {return value;}/*** Returns the value of this {@code Long} as a {@code float} after* a widening primitive conversion.* @jls 5.1.2 Widening Primitive Conversions*/public float floatValue() {return (float)value;}/*** Returns the value of this {@code Long} as a {@code double}* after a widening primitive conversion.* @jls 5.1.2 Widening Primitive Conversions*/public double doubleValue() {return (double)value;}/*** Returns a {@code String} object representing this* {@code Long}'s value. The value is converted to signed* decimal representation and returned as a string, exactly as if* the {@code long} value were given as an argument to the* {@link java.lang.Long#toString(long)} method.** @return a string representation of the value of this object in* base 10.*/public String toString() {return toString(value);}/*** Returns a hash code for this {@code Long}. The result is* the exclusive OR of the two halves of the primitive* {@code long} value held by this {@code Long}* object. That is, the hashcode is the value of the expression:** <blockquote>* {@code (int)(this.longValue()^(this.longValue()>>>32))}* </blockquote>** @return a hash code value for this object.*/@Overridepublic int hashCode() {return Long.hashCode(value);}/*** Returns a hash code for a {@code long} value; compatible with* {@code Long.hashCode()}.** @param value the value to hash* @return a hash code value for a {@code long} value.* @since 1.8*/public static int hashCode(long value) {return (int)(value ^ (value >>> 32));}/*** 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 Long} object that* contains the same {@code long} 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 Long) {return value == ((Long)obj).longValue();}return false;}/*** Determines the {@code long} value of the system property* with the specified name.** <p>The first argument is treated as the name of a system* property. System properties are accessible through the {@link* java.lang.System#getProperty(java.lang.String)} method. The* string value of this property is then interpreted as a {@code* long} value using the grammar supported by {@link Long#decode decode}* and a {@code Long} object representing this value is returned.** <p>If there is no property with the specified name, if the* specified name is empty or {@code null}, or if the property* does not have the correct numeric format, then {@code null} is* returned.** <p>In other words, this method returns a {@code Long} object* equal to the value of:** <blockquote>* {@code getLong(nm, null)}* </blockquote>** @param nm property name.* @return the {@code Long} value of the property.* @throws SecurityException for the same reasons as* {@link System#getProperty(String) System.getProperty}* @see java.lang.System#getProperty(java.lang.String)* @see java.lang.System#getProperty(java.lang.String, java.lang.String)*/public static Long getLong(String nm) {return getLong(nm, null);}/*** Determines the {@code long} value of the system property* with the specified name.** <p>The first argument is treated as the name of a system* property. System properties are accessible through the {@link* java.lang.System#getProperty(java.lang.String)} method. The* string value of this property is then interpreted as a {@code* long} value using the grammar supported by {@link Long#decode decode}* and a {@code Long} object representing this value is returned.** <p>The second argument is the default value. A {@code Long} object* that represents the value of the second argument is returned if there* is no property of the specified name, if the property does not have* the correct numeric format, or if the specified name is empty or null.** <p>In other words, this method returns a {@code Long} object equal* to the value of:** <blockquote>* {@code getLong(nm, new Long(val))}* </blockquote>** but in practice it may be implemented in a manner such as:** <blockquote><pre>* Long result = getLong(nm, null);* return (result == null) ? new Long(val) : result;* </pre></blockquote>** to avoid the unnecessary allocation of a {@code Long} object when* the default value is not needed.** @param nm property name.* @param val default value.* @return the {@code Long} value of the property.* @throws SecurityException for the same reasons as* {@link System#getProperty(String) System.getProperty}* @see java.lang.System#getProperty(java.lang.String)* @see java.lang.System#getProperty(java.lang.String, java.lang.String)*/public static Long getLong(String nm, long val) {Long result = Long.getLong(nm, null);return (result == null) ? Long.valueOf(val) : result;}/*** Returns the {@code long} value of the system property with* the specified name. The first argument is treated as the name* of a system property. System properties are accessible through* the {@link java.lang.System#getProperty(java.lang.String)}* method. The string value of this property is then interpreted* as a {@code long} value, as per the* {@link Long#decode decode} method, and a {@code Long} object* representing this value is returned; in summary:** <ul>* <li>If the property value begins with the two ASCII characters* {@code 0x} or the ASCII character {@code #}, not followed by* a minus sign, then the rest of it is parsed as a hexadecimal integer* exactly as for the method {@link #valueOf(java.lang.String, int)}* with radix 16.* <li>If the property value begins with the ASCII character* {@code 0} followed by another character, it is parsed as* an octal integer exactly as by the method {@link* #valueOf(java.lang.String, int)} with radix 8.* <li>Otherwise the property value is parsed as a decimal* integer exactly as by the method* {@link #valueOf(java.lang.String, int)} with radix 10.* </ul>** <p>Note that, in every case, neither {@code L}* ({@code '\u005Cu004C'}) nor {@code l}* ({@code '\u005Cu006C'}) is permitted to appear at the end* of the property value as a type indicator, as would be* permitted in Java programming language source code.** <p>The second argument is the default value. The default value is* returned if there is no property of the specified name, if the* property does not have the correct numeric format, or if the* specified name is empty or {@code null}.** @param nm property name.* @param val default value.* @return the {@code Long} value of the property.* @throws SecurityException for the same reasons as* {@link System#getProperty(String) System.getProperty}* @see System#getProperty(java.lang.String)* @see System#getProperty(java.lang.String, java.lang.String)*/public static Long getLong(String nm, Long val) {String v = null;try {v = System.getProperty(nm);} catch (IllegalArgumentException | NullPointerException e) {}if (v != null) {try {return Long.decode(v);} catch (NumberFormatException e) {}}return val;}/*** Compares two {@code Long} objects numerically.** @param anotherLong the {@code Long} to be compared.* @return the value {@code 0} if this {@code Long} is* equal to the argument {@code Long}; a value less than* {@code 0} if this {@code Long} is numerically less* than the argument {@code Long}; and a value greater* than {@code 0} if this {@code Long} is numerically* greater than the argument {@code Long} (signed* comparison).* @since 1.2*/public int compareTo(Long anotherLong) {return compare(this.value, anotherLong.value);}/*** Compares two {@code long} values numerically.* The value returned is identical to what would be returned by:* <pre>* Long.valueOf(x).compareTo(Long.valueOf(y))* </pre>** @param x the first {@code long} to compare* @param y the second {@code long} 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(long x, long y) {return (x < y) ? -1 : ((x == y) ? 0 : 1);}/*** Compares two {@code long} values numerically treating the values* as unsigned.** @param x the first {@code long} to compare* @param y the second {@code long} 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 1.8*/public static int compareUnsigned(long x, long y) {return compare(x + MIN_VALUE, y + MIN_VALUE);}/*** Returns the unsigned quotient of dividing the first argument by* the second where each argument and the result is interpreted as* an unsigned value.** <p>Note that in two's complement arithmetic, the three other* basic arithmetic operations of add, subtract, and multiply are* bit-wise identical if the two operands are regarded as both* being signed or both being unsigned. Therefore separate {@code* addUnsigned}, etc. methods are not provided.** @param dividend the value to be divided* @param divisor the value doing the dividing* @return the unsigned quotient of the first argument divided by* the second argument* @see #remainderUnsigned* @since 1.8*/public static long divideUnsigned(long dividend, long divisor) {if (divisor < 0L) { // signed comparison// Answer must be 0 or 1 depending on relative magnitude// of dividend and divisor.return (compareUnsigned(dividend, divisor)) < 0 ? 0L :1L;}if (dividend > 0) // Both inputs non-negativereturn dividend/divisor;else {/** For simple code, leveraging BigInteger. Longer and faster* code written directly in terms of operations on longs is* possible; see "Hacker's Delight" for divide and remainder* algorithms.*/return toUnsignedBigInteger(dividend).divide(toUnsignedBigInteger(divisor)).longValue();}}/*** Returns the unsigned remainder from dividing the first argument* by the second where each argument and the result is interpreted* as an unsigned value.** @param dividend the value to be divided* @param divisor the value doing the dividing* @return the unsigned remainder of the first argument divided by* the second argument* @see #divideUnsigned* @since 1.8*/public static long remainderUnsigned(long dividend, long divisor) {if (dividend > 0 && divisor > 0) { // signed comparisonsreturn dividend % divisor;} else {if (compareUnsigned(dividend, divisor) < 0) // Avoid explicit check for 0 divisorreturn dividend;elsereturn toUnsignedBigInteger(dividend).remainder(toUnsignedBigInteger(divisor)).longValue();}}// Bit Twiddling/*** The number of bits used to represent a {@code long} value in two's* complement binary form.** @since 1.5*/@Native public static final int SIZE = 64;/*** The number of bytes used to represent a {@code long} value in two's* complement binary form.** @since 1.8*/public static final int BYTES = SIZE / Byte.SIZE;/*** Returns a {@code long} value with at most a single one-bit, in the* position of the highest-order ("leftmost") one-bit in the specified* {@code long} value. Returns zero if the specified value has no* one-bits in its two's complement binary representation, that is, if it* is equal to zero.** @param i the value whose highest one bit is to be computed* @return a {@code long} value with a single one-bit, in the position* of the highest-order one-bit in the specified value, or zero if* the specified value is itself equal to zero.* @since 1.5*/public static long highestOneBit(long i) {// HD, Figure 3-1i |= (i >> 1);i |= (i >> 2);i |= (i >> 4);i |= (i >> 8);i |= (i >> 16);i |= (i >> 32);return i - (i >>> 1);}/*** Returns a {@code long} value with at most a single one-bit, in the* position of the lowest-order ("rightmost") one-bit in the specified* {@code long} value. Returns zero if the specified value has no* one-bits in its two's complement binary representation, that is, if it* is equal to zero.** @param i the value whose lowest one bit is to be computed* @return a {@code long} value with a single one-bit, in the position* of the lowest-order one-bit in the specified value, or zero if* the specified value is itself equal to zero.* @since 1.5*/public static long lowestOneBit(long i) {// HD, Section 2-1return i & -i;}/*** Returns the number of zero bits preceding the highest-order* ("leftmost") one-bit in the two's complement binary representation* of the specified {@code long} value. Returns 64 if the* specified value has no one-bits in its two's complement representation,* in other words if it is equal to zero.** <p>Note that this method is closely related to the logarithm base 2.* For all positive {@code long} values x:* <ul>* <li>floor(log<sub>2</sub>(x)) = {@code 63 - numberOfLeadingZeros(x)}* <li>ceil(log<sub>2</sub>(x)) = {@code 64 - numberOfLeadingZeros(x - 1)}* </ul>** @param i the value whose number of leading zeros is to be computed* @return the number of zero bits preceding the highest-order* ("leftmost") one-bit in the two's complement binary representation* of the specified {@code long} value, or 64 if the value* is equal to zero.* @since 1.5*/public static int numberOfLeadingZeros(long i) {// HD, Figure 5-6if (i == 0)return 64;int n = 1;int x = (int)(i >>> 32);if (x == 0) { n += 32; x = (int)i; }if (x >>> 16 == 0) { n += 16; x <<= 16; }if (x >>> 24 == 0) { n += 8; x <<= 8; }if (x >>> 28 == 0) { n += 4; x <<= 4; }if (x >>> 30 == 0) { n += 2; x <<= 2; }n -= x >>> 31;return n;}/*** Returns the number of zero bits following the lowest-order ("rightmost")* one-bit in the two's complement binary representation of the specified* {@code long} value. Returns 64 if the specified value has no* one-bits in its two's complement representation, in other words if it is* equal to zero.** @param i the value whose number of trailing zeros is to be computed* @return the number of zero bits following the lowest-order ("rightmost")* one-bit in the two's complement binary representation of the* specified {@code long} value, or 64 if the value is equal* to zero.* @since 1.5*/public static int numberOfTrailingZeros(long i) {// HD, Figure 5-14int x, y;if (i == 0) return 64;int n = 63;y = (int)i; if (y != 0) { n = n -32; x = y; } else x = (int)(i>>>32);y = x <<16; if (y != 0) { n = n -16; x = y; }y = x << 8; if (y != 0) { n = n - 8; x = y; }y = x << 4; if (y != 0) { n = n - 4; x = y; }y = x << 2; if (y != 0) { n = n - 2; x = y; }return n - ((x << 1) >>> 31);}/*** Returns the number of one-bits in the two's complement binary* representation of the specified {@code long} value. This function is* sometimes referred to as the <i>population count</i>.** @param i the value whose bits are to be counted* @return the number of one-bits in the two's complement binary* representation of the specified {@code long} value.* @since 1.5*/public static int bitCount(long i) {// HD, Figure 5-14i = i - ((i >>> 1) & 0x5555555555555555L);i = (i & 0x3333333333333333L) + ((i >>> 2) & 0x3333333333333333L);i = (i + (i >>> 4)) & 0x0f0f0f0f0f0f0f0fL;i = i + (i >>> 8);i = i + (i >>> 16);i = i + (i >>> 32);return (int)i & 0x7f;}/*** Returns the value obtained by rotating the two's complement binary* representation of the specified {@code long} value left by the* specified number of bits. (Bits shifted out of the left hand, or* high-order, side reenter on the right, or low-order.)** <p>Note that left rotation with a negative distance is equivalent to* right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,* distance)}. Note also that rotation by any multiple of 64 is a* no-op, so all but the last six bits of the rotation distance can be* ignored, even if the distance is negative: {@code rotateLeft(val,* distance) == rotateLeft(val, distance & 0x3F)}.** @param i the value whose bits are to be rotated left* @param distance the number of bit positions to rotate left* @return the value obtained by rotating the two's complement binary* representation of the specified {@code long} value left by the* specified number of bits.* @since 1.5*/public static long rotateLeft(long i, int distance) {return (i << distance) | (i >>> -distance);}/*** Returns the value obtained by rotating the two's complement binary* representation of the specified {@code long} value right by the* specified number of bits. (Bits shifted out of the right hand, or* low-order, side reenter on the left, or high-order.)** <p>Note that right rotation with a negative distance is equivalent to* left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,* distance)}. Note also that rotation by any multiple of 64 is a* no-op, so all but the last six bits of the rotation distance can be* ignored, even if the distance is negative: {@code rotateRight(val,* distance) == rotateRight(val, distance & 0x3F)}.** @param i the value whose bits are to be rotated right* @param distance the number of bit positions to rotate right* @return the value obtained by rotating the two's complement binary* representation of the specified {@code long} value right by the* specified number of bits.* @since 1.5*/public static long rotateRight(long i, int distance) {return (i >>> distance) | (i << -distance);}/*** Returns the value obtained by reversing the order of the bits in the* two's complement binary representation of the specified {@code long}* value.** @param i the value to be reversed* @return the value obtained by reversing order of the bits in the* specified {@code long} value.* @since 1.5*/public static long reverse(long i) {// HD, Figure 7-1i = (i & 0x5555555555555555L) << 1 | (i >>> 1) & 0x5555555555555555L;i = (i & 0x3333333333333333L) << 2 | (i >>> 2) & 0x3333333333333333L;i = (i & 0x0f0f0f0f0f0f0f0fL) << 4 | (i >>> 4) & 0x0f0f0f0f0f0f0f0fL;i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL;i = (i << 48) | ((i & 0xffff0000L) << 16) |((i >>> 16) & 0xffff0000L) | (i >>> 48);return i;}/*** Returns the signum function of the specified {@code long} value. (The* return value is -1 if the specified value is negative; 0 if the* specified value is zero; and 1 if the specified value is positive.)** @param i the value whose signum is to be computed* @return the signum function of the specified {@code long} value.* @since 1.5*/public static int signum(long i) {// HD, Section 2-7return (int) ((i >> 63) | (-i >>> 63));}/*** Returns the value obtained by reversing the order of the bytes in the* two's complement representation of the specified {@code long} value.** @param i the value whose bytes are to be reversed* @return the value obtained by reversing the bytes in the specified* {@code long} value.* @since 1.5*/public static long reverseBytes(long i) {i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL;return (i << 48) | ((i & 0xffff0000L) << 16) |((i >>> 16) & 0xffff0000L) | (i >>> 48);}/*** Adds two {@code long} values together as per the + operator.** @param a the first operand* @param b the second operand* @return the sum of {@code a} and {@code b}* @see java.util.function.BinaryOperator* @since 1.8*/public static long sum(long a, long b) {return a + b;}/*** Returns the greater of two {@code long} values* as if by calling {@link Math#max(long, long) Math.max}.** @param a the first operand* @param b the second operand* @return the greater of {@code a} and {@code b}* @see java.util.function.BinaryOperator* @since 1.8*/public static long max(long a, long b) {return Math.max(a, b);}/*** Returns the smaller of two {@code long} values* as if by calling {@link Math#min(long, long) Math.min}.** @param a the first operand* @param b the second operand* @return the smaller of {@code a} and {@code b}* @see java.util.function.BinaryOperator* @since 1.8*/public static long min(long a, long b) {return Math.min(a, b);}/** use serialVersionUID from JDK 1.0.2 for interoperability */@Native private static final long serialVersionUID = 4290774380558885855L;
}Long Source
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