Java中的 AtomicReferenceArray weakCompareAndSetVolatile() 方法及示例

AtomicReferenceArray类的weakCompareAndSetVolatile()方法用于将索引 i 处的元素的值自动设置为 newValue，如果当前值等于作为参数传递的预期值，则 AtomicReferenceArray 的 newValue。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(int i,
                                 E expectedValue,
                                 E newValue)

参数：此方法接受i ，它是 AtomicReferenceArray 的索引来执行操作， expectedValue是期望值， newValue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 AtomicReferenceArray
// weakCompareAndSetVolatile() method
  
import java.util.concurrent.atomic.AtomicReferenceArray;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // create an atomic reference object.
        AtomicReferenceArray ref
            = new AtomicReferenceArray(5);
  
        // set some value
        ref.set(1, 1234.00);
        ref.set(0, 2234.00);
        ref.set(2, 3234.00);
  
        // apply weakCompareAndSetVolatile()
        boolean result
            = ref.weakCompareAndSetVolatile(1, 124.00,
                                            234.32);
  
        // print value
        System.out.println("Setting new value"
                           + " is successful = "
                           + result);
  
        System.out.println("Value of index 1 = "
                           + ref.get(1));
    }
}

输出：

方案二：

// Java program to demonstrate AtomicReferenceArray
// weakCompareAndSetVolatile() method
  
import java.util.concurrent.atomic.AtomicReferenceArray;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // create an atomic reference object.
        AtomicReferenceArray ref
            = new AtomicReferenceArray(5);
  
        // set some value
        ref.set(0, "AMANDIP");
        ref.set(1, "AMAN");
  
        // apply weakCompareAndSetVolatile()
        boolean result
            = ref.weakCompareAndSetVolatile(
                0,
                "AMARDIP",
                "AMAR");
  
        // print value
        System.out.println("Setting new value"
                           + " is successful = "
                           + result);
  
        System.out.println("Value of index 0 = "
                           + ref.get(0));
    }
}

输出：

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