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AtomicInteger (Java Platform SE 6) - JDK 5 Documentation v6.0, Java 2 SDK 英文文档

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java.util.concurrent.atomic
Class AtomicInteger

java.lang.Object
  java.lang.Number
      java.util.concurrent.atomic.AtomicInteger

All Implemented Interfaces:

Serializable

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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

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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()           Returns the value of the specified number as a double.
float	floatValue()           Returns the value of the specified number as a float.
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()           Returns the value of the specified number as an int.
void	lazySet(int newValue)           Eventually sets to the given value.
long	longValue()           Returns the value of the specified number as a long.
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, shortValue

 

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

 

Constructor Detail

AtomicInteger

public AtomicInteger(int initialValue)

Creates a new AtomicInteger with the given initial value.

Parameters:

initialValue - the initial value

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AtomicInteger

public AtomicInteger()

Creates a new AtomicInteger with initial value 0.

Method Detail

get

public final int get()

Gets the current value.

Returns:

the current value

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set

public final void set(int newValue)

Sets to the given value.

Parameters:

newValue - the new value

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lazySet

public final void lazySet(int newValue)

Eventually sets to the given value.

Parameters:

newValue - the new value

Since:

1.6

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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

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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.

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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.

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getAndIncrement

public final int getAndIncrement()

Atomically increments by one the current value.

Returns:

the previous value

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getAndDecrement

public final int getAndDecrement()

Atomically decrements by one the current value.

Returns:

the previous value

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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

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incrementAndGet

public final int incrementAndGet()

Atomically increments by one the current value.

Returns:

the updated value

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decrementAndGet

public final int decrementAndGet()

Atomically decrements by one the current value.

Returns:

the updated value

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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

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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.

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intValue

public int intValue()

Description copied from class: Number

Returns the value of the specified number as an int. This may involve rounding or truncation.

Specified by:

intValue in class Number

Returns:

the numeric value represented by this object after conversion to type int.

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longValue

public long longValue()

Description copied from class: Number

Returns the value of the specified number as a long. This may involve rounding or truncation.

Specified by:

longValue in class Number

Returns:

the numeric value represented by this object after conversion to type long.

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floatValue

public float floatValue()

Description copied from class: Number

Returns the value of the specified number as a float. This may involve rounding.

Specified by:

floatValue in class Number

Returns:

the numeric value represented by this object after conversion to type float.

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doubleValue

public double doubleValue()

Description copied from class: Number

Returns the value of the specified number as a double. This may involve rounding.

Specified by:

doubleValue in class Number

Returns:

the numeric value represented by this object after conversion to type double.

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