Long class wraps a value of the primitive type
long in an object. An object of type Long
contains a single field whose type is long.
In addition, this class provides several methods for converting a
long to a String and a
String to a long, as well as other
constants and methods useful when dealing with a long.
Implementation note: The implementations of the "bit twiddling" methods (such as highestOneBit and numberOfTrailingZeros ) are based on material from Henry S. Warren, Jr.'s Hacker's Delight, (Addison Wesley, 2002).
Long object that
represents the specified long argument.Long object that
represents the long value indicated by the
String parameter. The string is converted to a
long value in exactly the manner used by the
parseLong method for radix 10.long can
have, 263-1.long can
have, -263.Class instance representing the primitive type
long.Long as a
byte.Long objects numerically.In the foregoing description, the notation sgn(expression) designates the mathematical signum function, which is defined to return one of -1, 0, or 1 according to whether the value of expression is negative, zero or positive. The implementor must ensure sgn(x.compareTo(y)) == -sgn(y.compareTo(x)) for all x and y. (This implies that x.compareTo(y) must throw an exception iff y.compareTo(x) throws an exception.)
The implementor must also ensure that the relation is transitive: (x.compareTo(y)>0 && y.compareTo(z)>0) implies x.compareTo(z)>0.
Finally, the implementer must ensure that x.compareTo(y)==0 implies that sgn(x.compareTo(z)) == sgn(y.compareTo(z)), for all z.
It is strongly recommended, but not strictly required that (x.compareTo(y)==0) == (x.equals(y)). Generally speaking, any class that implements the Comparable interface and violates this condition should clearly indicate this fact. The recommended language is "Note: this class has a natural ordering that is inconsistent with equals."
String into a Long.
Accepts decimal, hexadecimal, and octal numbers given by the
following grammar:
DecimalNumeral, HexDigits, and OctalDigits are defined in §3.10.1 of the Java Language Specification.
- DecodableString:
- Signopt DecimalNumeral
- Signopt
0xHexDigits- Signopt
0XHexDigits- Signopt
#HexDigits- Signopt
0OctalDigits
- Sign:
-
The sequence of characters following an (optional) negative
sign and/or radix specifier ("0x",
"0X", "#", or
leading zero) is parsed as by the Long.parseLong
method with the indicated radix (10, 16, or 8). This sequence
of characters must represent a positive value or a NumberFormatException
will be thrown. The result is negated
if first character of the specified String is the
minus sign. No whitespace characters are permitted in the
String.
Long as a
double.true if and only if the argument is not
null and is a Long object that
contains the same long value as this object.Long as a
float.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
method. The
string value of this property is then interpreted as a
long value and a Long object
representing this value is returned. Details of possible
numeric formats can be found with the definition of
getProperty.
If there is no property with the specified name, if the
specified name is empty or null, or if the
property does not have the correct numeric format, then
null is returned.
In other words, this method returns a Long object equal to
the value of:
getLong(nm, null)
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
method. The
string value of this property is then interpreted as a
long value and a Long object
representing this value is returned. Details of possible
numeric formats can be found with the definition of
getProperty.
The second argument is the default value. A 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.
In other words, this method returns a Long object equal
to the value of:
getLong(nm, new Long(val))
to avoid the unnecessary allocation of aLong result = getLong(nm, null); return (result == null) ? new Long(val) : result;
Long object when
the default value is not needed.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
method. The string value of this property is then interpreted
as a long value, as per the
Long.decode method, and a Long object
representing this value is returned.
0x or the ASCII character #, not followed by
a minus sign, then the rest of it is parsed as a hexadecimal integer
exactly as for the method
with radix 16.
0 followed by another character, it is parsed as
an octal integer exactly as by the method
with radix 8.
Note that, in every case, neither L
('\u004C') nor l
('\u006C') 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.
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 null.
Long. The result is
the exclusive OR of the two halves of the primitive
long value held by this Long
object. That is, the hashcode is the value of the expression:
(int)(this.longValue()^(this.longValue()>>>32))
Long as an
int.Long as a
long value.wait methods.
The awakened thread will not be able to proceed until the current thread relinquishes the lock on this object. The awakened thread will compete in the usual manner with any other threads that might be actively competing to synchronize on this object; for example, the awakened thread enjoys no reliable privilege or disadvantage in being the next thread to lock this object.
This method should only be called by a thread that is the owner of this object's monitor. A thread becomes the owner of the object's monitor in one of three ways:
synchronized statement
that synchronizes on the object.
Class, by executing a
synchronized static method of that class.
Only one thread at a time can own an object's monitor.
wait methods.
The awakened threads will not be able to proceed until the current thread relinquishes the lock on this object. The awakened threads will compete in the usual manner with any other threads that might be actively competing to synchronize on this object; for example, the awakened threads enjoy no reliable privilege or disadvantage in being the next thread to lock this object.
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.
Note that this method is closely related to the logarithm base 2. For all positive long values x:
long. The characters in the string must all be
decimal digits, except that the first character may be an ASCII
minus sign '-' (\u002D') to
indicate a negative value. The resulting long
value is returned, exactly as if the argument and the radix
10 were given as arguments to the
method.
Note that neither the character L
('\u004C') nor l
('\u006C') is permitted to appear at the end
of the string as a type indicator, as would be permitted in
Java programming language source 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
returns
a nonnegative value), except that the first character may be an
ASCII minus sign '-' ('\u002D') to
indicate a negative value. The resulting long
value is returned.
Note that neither the character L
('\u004C') nor l
('\u006C') 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
L or l may appear as a digit for a
radix greater than 22.
An exception of type NumberFormatException is
thrown if any of the following situations occurs:
null or is a string of
length zero.
radix is either smaller than java.lang.Character#MIN_RADIX
or larger than java.lang.Character#MAX_RADIX
.
'-' ('\u002d') provided that the
string is longer than length 1.
long.
Examples:
parseLong("0", 10) returns 0L
parseLong("473", 10) returns 473L
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
Note that left rotation with a negative distance is equivalent to right rotation: 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: rotateLeft(val, distance) == rotateLeft(val, distance & 0x3F).
Note that right rotation with a negative distance is equivalent to left rotation: 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: rotateRight(val, distance) == rotateRight(val, distance & 0x3F).
Long as a
short.long
argument as an unsigned integer in base 2.
The unsigned long value is the argument plus
264 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
0s. If the unsigned magnitude is zero, it is
represented by a single zero character '0'
('\u0030'); otherwise, the first character of
the representation of the unsigned magnitude will not be the
zero character. The characters '0'
('\u0030') and '1'
('\u0031') are used as binary digits.
long
argument as an unsigned integer in base 16.
The unsigned long value is the argument plus
264 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 0s. If the unsigned magnitude is zero, it
is represented by a single zero character '0'
('\u0030'); 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:
These are the characters0123456789abcdef
'\u0030' through
'\u0039' and '\u0061' through
'\u0066'. If uppercase letters are desired,
the
method may be called
on the result:
Long.toHexString(n).toUpperCase()
long
argument as an unsigned integer in base 8.
The unsigned long value is the argument plus
264 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
0s.
If the unsigned magnitude is zero, it is represented by a
single zero character '0'
('\u0030'); 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:
These are the characters01234567
'\u0030' through
'\u0037'.
If the radix is smaller than Character.MIN_RADIX
or larger than Character.MAX_RADIX, then the radix
10 is used instead.
If the first argument is negative, the first element of the
result is the ASCII minus sign '-'
('\u002d'). If the first argument is not
negative, no sign character appears in the result.
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 '0'
('\u0030'); otherwise, the first character of
the representation of the magnitude will not be the zero
character. The following ASCII characters are used as digits:
These are0123456789abcdefghijklmnopqrstuvwxyz
'\u0030' through
'\u0039' and '\u0061' through
'\u007a'. If radix is
N, then the first N of these characters
are used as radix-N digits in the order shown. Thus,
the digits for hexadecimal (radix 16) are
0123456789abcdef. If uppercase letters are
desired, the
method may
be called on the result:
Long.toString(n, 16).toUpperCase()
Long object holding the value
of the specified String. The argument is
interpreted as representing a signed decimal long,
exactly as if the argument were given to the
method. The result is a
Long object that represents the integer value
specified by the string.
In other words, this method returns a Long object
equal to the value of:
new Long(Long.parseLong(s))
Long object holding the value
extracted from the specified String when parsed
with the radix given by the second argument. The first
argument is interpreted as representing a signed
long in the radix specified by the second
argument, exactly as if the arguments were given to the
method. The result is a
Long object that represents the long
value specified by the string.
In other words, this method returns a Long object equal
to the value of:
new Long(Long.parseLong(s, radix))
The current thread must own this object's monitor. The thread
releases ownership of this monitor and waits until another thread
notifies threads waiting on this object's monitor to wake up
either through a call to the notify method or the
notifyAll method. The thread then waits until it can
re-obtain ownership of the monitor and resumes execution.
As in the one argument version, interrupts and spurious wakeups are possible, and this method should always be used in a loop:
synchronized (obj) {
while (<condition does not hold>)
obj.wait();
... // Perform action appropriate to condition
}
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.The current thread must own this object's monitor.
This method causes the current thread (call it T) to place itself in the wait set for this object and then to relinquish any and all synchronization claims on this object. Thread T becomes disabled for thread scheduling purposes and lies dormant until one of four things happens:
A thread can also wake up without being notified, interrupted, or timing out, a so-called spurious wakeup. While this will rarely occur in practice, applications must guard against it by testing for the condition that should have caused the thread to be awakened, and continuing to wait if the condition is not satisfied. In other words, waits should always occur in loops, like this one:
synchronized (obj) {
while (<condition does not hold>)
obj.wait(timeout);
... // Perform action appropriate to condition
}
(For more information on this topic, see Section 3.2.3 in Doug Lea's
"Concurrent Programming in Java (Second Edition)" (Addison-Wesley,
2000), or Item 50 in Joshua Bloch's "Effective Java Programming
Language Guide" (Addison-Wesley, 2001).
If the current thread is interrupted by another thread while it is waiting, then an InterruptedException is thrown. This exception is not thrown until the lock status of this object has been restored as described above.
Note that the wait method, as it places the current thread into the wait set for this object, unlocks only this object; any other objects on which the current thread may be synchronized remain locked while the thread waits.
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.
This method is similar to the wait method of one
argument, but it allows finer control over the amount of time to
wait for a notification before giving up. The amount of real time,
measured in nanoseconds, is given by:
1000000*timeout+nanos
In all other respects, this method does the same thing as the method of one argument. In particular, wait(0, 0) means the same thing as wait(0).
The current thread must own this object's monitor. The thread releases ownership of this monitor and waits until either of the following two conditions has occurred:
notify method
or the notifyAll method.
timeout
milliseconds plus nanos nanoseconds arguments, has
elapsed.
The thread then waits until it can re-obtain ownership of the monitor and resumes execution.
As in the one argument version, interrupts and spurious wakeups are possible, and this method should always be used in a loop:
synchronized (obj) {
while (<condition does not hold>)
obj.wait(timeout, nanos);
... // Perform action appropriate to condition
}
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.