Build 1.0_r1(from source)

java.util.concurrent.atomic
Class AtomicLong

java.lang.Object
  extended by java.lang.Number
      extended by java.util.concurrent.atomic.AtomicLong
All Implemented Interfaces:
Serializable

public class AtomicLong
extends Number
implements Serializable

A long value that may be updated atomically. See the java.util.concurrent.atomic package specification for description of the properties of atomic variables. An AtomicLong is used in applications such as atomically incremented sequence numbers, and cannot be used as a replacement for a Long. However, this class does extend Number to allow uniform access by tools and utilities that deal with numerically-based classes.

Since:
1.5
See Also:
Serialized Form

Field Summary
(package private) static boolean VM_SUPPORTS_LONG_CAS
          Record whether the underlying JVM supports lockless CompareAndSet for longs.
 
Constructor Summary
AtomicLong()
          Create a new AtomicLong with initial value 0.
AtomicLong(long initialValue)
          Create a new AtomicLong with the given initial value.
 
Method Summary
 long addAndGet(long delta)
          Atomically add the given value to current value.
 boolean compareAndSet(long expect, long update)
          Atomically set the value to the given updated value if the current value == the expected value.
 long decrementAndGet()
          Atomically decrement by one the current value.
 double doubleValue()
          Returns the double value which the receiver represents
 float floatValue()
          Returns the float value which the receiver represents
 long get()
          Get the current value.
 long getAndAdd(long delta)
          Atomically add the given value to current value.
 long getAndDecrement()
          Atomically decrement by one the current value.
 long getAndIncrement()
          Atomically increment by one the current value.
 long getAndSet(long newValue)
          Set to the give value and return the old value.
 long incrementAndGet()
          Atomically increment by one the current value.
 int intValue()
          Returns the int value which the receiver represents
 long longValue()
          Returns the long value which the receiver represents
 void set(long newValue)
          Set to the given value.
 String toString()
          Returns the String representation of the current value.
 boolean weakCompareAndSet(long expect, long update)
          Atomically set the value to the given updated value if the current value == the expected value.
 
Methods inherited from class java.lang.Number
byteValue, shortValue
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

VM_SUPPORTS_LONG_CAS

static final boolean VM_SUPPORTS_LONG_CAS
Record whether the underlying JVM supports lockless CompareAndSet for longs. While the unsafe.CompareAndSetLong method works in either case, some constructions should be handled at Java level to avoid locking user-visible locks.

Constructor Detail

AtomicLong

public AtomicLong(long initialValue)
Create a new AtomicLong with the given initial value.

Parameters:
initialValue - the initial value

AtomicLong

public AtomicLong()
Create a new AtomicLong with initial value 0.

Method Detail

get

public final long get()
Get the current value.

Returns:
the current value

set

public final void set(long newValue)
Set to the given value.

Parameters:
newValue - the new value

getAndSet

public final long getAndSet(long newValue)
Set to the give value and return the old value.

Parameters:
newValue - the new value
Returns:
the previous value

compareAndSet

public final boolean compareAndSet(long expect,
                                   long update)
Atomically set the value to the given updated value if the current value == the expected value.

Parameters:
expect - the expected value
update - the new value
Returns:
true if successful. False return indicates that the actual value was not equal to the expected value.

weakCompareAndSet

public final boolean weakCompareAndSet(long expect,
                                       long update)
Atomically set the value to the given updated value if the current value == the expected value. May fail spuriously.

Parameters:
expect - the expected value
update - the new value
Returns:
true if successful.

getAndIncrement

public final long getAndIncrement()
Atomically increment by one the current value.

Returns:
the previous value

getAndDecrement

public final long getAndDecrement()
Atomically decrement by one the current value.

Returns:
the previous value

getAndAdd

public final long getAndAdd(long delta)
Atomically add the given value to current value.

Parameters:
delta - the value to add
Returns:
the previous value

incrementAndGet

public final long incrementAndGet()
Atomically increment by one the current value.

Returns:
the updated value

decrementAndGet

public final long decrementAndGet()
Atomically decrement by one the current value.

Returns:
the updated value

addAndGet

public final long addAndGet(long delta)
Atomically add the given value to current value.

Parameters:
delta - the value to add
Returns:
the updated value

toString

public String toString()
Returns the String representation of the current value.

Overrides:
toString in class Object
Returns:
the String representation of the current value.

intValue

public int intValue()
Description copied from class: Number
Returns the int value which the receiver represents

Specified by:
intValue in class Number
Returns:
int the value of the receiver.

longValue

public long longValue()
Description copied from class: Number
Returns the long value which the receiver represents

Specified by:
longValue in class Number
Returns:
long the value of the receiver.

floatValue

public float floatValue()
Description copied from class: Number
Returns the float value which the receiver represents

Specified by:
floatValue in class Number
Returns:
float the value of the receiver.

doubleValue

public double doubleValue()
Description copied from class: Number
Returns the double value which the receiver represents

Specified by:
doubleValue in class Number
Returns:
double the value of the receiver.

Build 1.0_r1(from source)

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