Java中的 AtomicReference weakCompareAndSetVolatile() 方法及示例

AtomicReference类的weakCompareAndSetVolatile()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 VarHandle.weakCompareAndSet(Java.lang.Object…) 指定的记忆效应更新值。如果为 AtomicRefrence 设置新值成功，则此方法返回 true。

句法：

public final boolean 
       weakCompareAndSetVolatile(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weakCompareAndSetVolatile() 方法：
方案一：

// Java program to demonstrate
// AtomicReference.weakCompareAndSetVolatile() method
  
import java.util.concurrent.atomic.AtomicReference;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // create an atomic reference object.
        AtomicReference ref
            = new AtomicReference();
  
        // set some value
        ref.set(1234.00);
  
        // apply weakCompareAndSetVolatile()
        boolean result
            = ref.weakCompareAndSetVolatile(124.00,
                                            234.32);
  
        // print value
        System.out.println("Setting new value"
                           + " is successful = "
                           + result);
  
        System.out.println("Value = " + ref.get());
    }
}

输出：

方案二：

// Java program to demonstrate
// AtomicReference.weakCompareAndSetVolatile() 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("GFG");
  
        // apply weakCompareAndSetVolatile()
        boolean result
            = ref.weakCompareAndSetVolatile(
                "GFG",
                "GEEKS FOR GEEKS");
  
        // print value
        System.out.println("Setting new value"
                           + " is successful = "
                           + result);
        System.out.println("Value  = " + ref.get());
    }
}

输出：

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