Java中的AtomicReferenceArray accumulateAndGet()方法及示例

AtomicReferenceArray类的accumulateAndGet()方法用于以将给定 accumulatorFunction 应用于当前值和给定值的结果原子地更新 AtomicReferenceArray 的索引 i 处的元素，并返回更新后的值。 accumulatorFunction 应该没有副作用，因为当尝试更新由于线程之间的争用而失败时，它可能会被重新应用。该函数应用索引 i 处的当前值作为其第一个参数，并将给定的更新作为第二个参数。

句法：

public final E accumulateAndGet(int i, E x,
     BinaryOperator accumulatorFunction)

参数：此方法接受：

• i是执行操作的 AtomicReferenceArray 的索引，接受，
• x是更新后的值，并且
• accumulatorFunction是两个参数的无副作用函数。

返回值：该方法返回更新后的值。

下面的程序说明了 accumulateAndGet() 方法：
方案一：

// Java program to demonstrate
// accumulateAndGet() method
  
import java.util.concurrent.atomic.*;
import java.util.function.BinaryOperator;
  
public class GFG {
    public static void main(String args[])
    {
        // an array
        Integer a[] = { 123, 1232, 1433, 134, 13415, 1343 };
  
        // AtomicReferenceArray with array
        AtomicReferenceArray array
            = new AtomicReferenceArray<>(a);
  
        // Print AtomicReferenceArray
        System.out.println(
            "The AtomicReferenceArray before update\n: "
            + array);
  
        // Index and Value to apply accumulateAndGet
        int index = 2;
        int E = 343;
  
        // Declaring the accumulatorFunction
        // applying function to add value as string
        BinaryOperator add
            = (u, v)
            -> u.toString()
                   + v.toString();
  
        // apply accumulateAndGet()
        array.accumulateAndGet(index, E, add);
  
        // print AtomicReferenceArray
        System.out.println(
            "The AtomicReferenceArray "
            + "after update \n: "
            + array);
    }
}

输出：

方案二：

// Java program to demonstrate
// accumulateAndGet() method
  
import java.util.concurrent.atomic.*;
import java.util.function.BinaryOperator;
  
public class GFG {
    public static void main(String args[])
    {
        // an array
        String a[] = { "GFG", "JS" };
  
        // AtomicReferenceArray with array
        AtomicReferenceArray arra
            = new AtomicReferenceArray<>(a);
  
        // Print AtomicReferenceArray
        System.out.println(
            "The AtomicReferenceArray"
            + " before update \n: "
            + array);
  
        // Index and Value to apply accumulateAndGet
        int index = 1;
        String E = " PYTHON";
  
        // Declaring the accumulatorFunction
        // applying function to add value as string
        BinaryOperator add
            = (u, v)
            -> u.toString()
                   + " and "
                   + v.toString();
  
        // apply accumulateAndGet()
        array.accumulateAndGet(index, E, add);
  
        // print AtomicReferenceArray
        System.out.println(
            "The AtomicReferenceArray"
            + " after update \n: "
            + array);
    }
}

输出：

参考资料： https://docs.oracle.com/javase/10/docs/api/java /util/concurrent/atomic/AtomicReferenceArray.html#accumulateAndGet(int, E, Java Java 函数)