如果AtomicReference对象的当前值(称为见证值)等于期望值并返回见证值,则使用AtomicReference类的compareAndExchangeAcquire()方法将Atommic值以原子方式将newValue设置为AtomicReference对象。此方法以与memory_order_acquire排序兼容的内存排序效果交换该值。
用法:
public final V compareAndExchangeAcquire(V expectedValue, V newValue)
参数:该方法接受ExpectedValue(期望值)和newValue(新值)来设置新值。
返回值:此方法返回见证值,如果成功,它将与期望值相同。
以下示例程序旨在说明compareAndExchangeAcquire()方法:
程序1:
// Java program to demonstrate
// AtomicReference.compareAndExchangeAcquire() method
import java.util.concurrent.atomic.AtomicReference;
public class GFG {
public static void main(String[] args)
{
// create an atomic reference object
// which stores Integer.
AtomicReference<Double> ref
= new AtomicReference<Double>();
// set some value
ref.set(0.199);
// apply compareAndExchangeAcquire()
double oldValue
= ref.compareAndExchangeAcquire(
0.199,
999.999);
// print value
System.out.println("Witness Value = "
+ oldValue);
}
}
输出:
程序2:
// Java program to demonstrate
// AtomicReference.compareAndExchangeAcquire() method
import java.util.concurrent.atomic.AtomicReference;
public class GFG {
public static void main(String[] args)
{
// create an atomic reference object.
AtomicReference<String> ref
= new AtomicReference<String>();
// set some value
ref.set("Weeks");
// apply compareAndExchangeAcquire()
String oldValue
= ref.compareAndExchangeAcquire(
"Weeks",
"Days");
// print value
System.out.println("Witness Value = "
+ oldValue);
}
}
输出:
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注:本文由纯净天空筛选整理自AmanSingh2210大神的英文原创作品 AtomicReference compareAndExchangeAcquire() method in Java with Examples。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。