Java中的 AtomicReference weakCompareAndSetAcquire() 方法及示例

AtomicReference类的weakCompareAndSetAcquire()方法用于将 AtomicReference 的值自动设置为 newValue，如果当前值等于作为参数传递的 expectedValue。此方法使用与 memory_order_acquire 排序兼容的内存排序效果更新值。如果为 AtomicRefrence 设置新值成功，则此方法返回 true。

句法：

public final boolean
 weakCompareAndSetAcquire(V expectedValue,
                          V newValue)

参数：此方法接受期望值和newValue ，这是要设置的新值。
返回值：如果成功，此方法返回true。

下面的程序说明了weakCompareAndSetAcquire() 方法：

方案一：

Java

// Java program to demonstrate
// AtomicReference.weakCompareAndSetAcquire() 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 ref
            = new AtomicReference();
 
        // set some value
        ref.set(11111111L);
 
        // apply weakCompareAndSetAcquire()
        boolean result
            = ref.weakCompareAndSetAcquire(
                1111111111111L,
                999999L);
 
        // print value
        System.out.println("Setting new value"
                           + " is successful = "
                           + result);
        System.out.println("Value = " + ref.get());
    }
}

输出：

方案二：

Java

// Java program to demonstrate
// AtomicReference.weakCompareAndSetAcquire() method
 
import java.util.concurrent.atomic.AtomicReference;
 
public class GFG {
    public static void main(String[] args)
    {
 
        // create an atomic reference object
        // which stores String.
        AtomicReference ref
            = new AtomicReference();
 
        // set some value
        ref.set("WELCOME TO GEEKS FOR GEEKS");
 
        // apply weakCompareAndSetAcquire()
        boolean result
            = ref.weakCompareAndSetAcquire(
                "WELCOME TO GEEKS FOR GEEKS",
                "WELCOLME GEEKS");
 
        // print value
        System.out.println("Setting new value"
                           + " is successful = "
                           + result);
        System.out.println("Value  = " + ref.get());
    }
}

输出：

参考资料： https: Java/util/concurrent/atomic/AtomicReference.html#weakCompareAndSetAcquire(V, V)