java.util.concurrent.atomic

Class AtomicInteger

Implemented Interfaces:
Serializable

public class AtomicInteger
extends Number
implements Serializable

An int value that may be updated atomically. See the java.util.concurrent.atomic package specification for description of the properties of atomic variables. An AtomicInteger is used in applications such as atomically incremented counters, and cannot be used as a replacement for an Integer. 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

Constructor Summary

AtomicInteger()
Creates a new AtomicInteger with initial value 0.
AtomicInteger(int initialValue)
Creates a new AtomicInteger with the given initial value.

Method Summary

int
addAndGet(int delta)
Atomically adds the given value to the current value.
boolean
compareAndSet(int expect, int update)
Atomically sets the value to the given updated value if the current value == the expected value.
int
decrementAndGet()
Atomically decrements by one the current value.
double
doubleValue()
float
floatValue()
int
get()
Gets the current value.
int
getAndAdd(int delta)
Atomically adds the given value to the current value.
int
getAndDecrement()
Atomically decrements by one the current value.
int
getAndIncrement()
Atomically increments by one the current value.
int
getAndSet(int newValue)
Atomically sets to the given value and returns the old value.
int
incrementAndGet()
Atomically increments by one the current value.
int
intValue()
void
lazySet(int newValue)
Eventually sets to the given value.
long
longValue()
void
set(int newValue)
Sets to the given value.
String
toString()
Returns the String representation of the current value.
boolean
weakCompareAndSet(int expect, int update)
Atomically sets the value to the given updated value if the current value == the expected value.

Methods inherited from class java.lang.Number

byteValue, doubleValue, floatValue, intValue, longValue, shortValue

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

AtomicInteger

public AtomicInteger()
Creates a new AtomicInteger with initial value 0.

AtomicInteger

public AtomicInteger(int initialValue)
Creates a new AtomicInteger with the given initial value.
Parameters:
initialValue - the initial value

Method Details

addAndGet

public final int addAndGet(int delta)
Atomically adds the given value to the current value.
Parameters:
delta - the value to add
Returns:
the updated value

compareAndSet

public final boolean compareAndSet(int expect,
                                   int update)
Atomically sets 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.

decrementAndGet

public final int decrementAndGet()
Atomically decrements by one the current value.
Returns:
the updated value

doubleValue

public double doubleValue()
Overrides:
doubleValue in interface Number

floatValue

public float floatValue()
Overrides:
floatValue in interface Number

get

public final int get()
Gets the current value.
Returns:
the current value

getAndAdd

public final int getAndAdd(int delta)
Atomically adds the given value to the current value.
Parameters:
delta - the value to add
Returns:
the previous value

getAndDecrement

public final int getAndDecrement()
Atomically decrements by one the current value.
Returns:
the previous value

getAndIncrement

public final int getAndIncrement()
Atomically increments by one the current value.
Returns:
the previous value

getAndSet

public final int getAndSet(int newValue)
Atomically sets to the given value and returns the old value.
Parameters:
newValue - the new value
Returns:
the previous value

incrementAndGet

public final int incrementAndGet()
Atomically increments by one the current value.
Returns:
the updated value

intValue

public int intValue()
Overrides:
intValue in interface Number

lazySet

public final void lazySet(int newValue)
Eventually sets to the given value.
Parameters:
newValue - the new value
Since:
1.6

longValue

public long longValue()
Overrides:
longValue in interface Number

set

public final void set(int newValue)
Sets to the given value.
Parameters:
newValue - the new value

toString

public String toString()
Returns the String representation of the current value.
Overrides:
toString in interface Object
Returns:
the String representation of the current value.

weakCompareAndSet

public final boolean weakCompareAndSet(int expect,
                                       int update)
Atomically sets the value to the given updated value if the current value == the expected value. May fail spuriously and does not provide ordering guarantees, so is only rarely an appropriate alternative to compareAndSet.
Parameters:
expect - the expected value
update - the new value
Returns:
true if successful.