AtomicReference getAndAccumulate() method in Java with Examples

Last Updated : 15 Apr, 2021

The getAndAccumulate() method of a AtomicReference class is used to atomically updates the current value of AtomicReference with the results of applying the given accumulatorFunction to the current and given values and returns the previous value. The accumulatorFunction should be side-effect-free, since it may be re-applied when attempted updates fail due to contention among threads. The function is applied with the current value as its first argument, and the given update as the second argument.
Syntax:

public final E getAndAccumulate(E x,
     BinaryOperator<E> accumulatorFunction)

Parameters: This method accepts:

x which is the updated value and
accumulatorFunction which is a side-effect-free function of two arguments.

Return value: This method returns the previous value.
Below programs illustrate the getAndAccumulate() method:
Program 1:

Java

// Java program to demonstrate
// AtomicReference.getAndAccumulate() method

import java.util.concurrent.atomic.*;
import java.util.function.BinaryOperator;

public class GFG {
    public static void main(String args[])
    {

        // AtomicReference with value
        AtomicReference<Integer> ref
            = new AtomicReference<>(3456);

        // Value to apply getAndAccumulate
        int x = 45654;

        // Declaring the accumulatorFunction
        // applying function to add value as string
        BinaryOperator add
            = (u, v) -> u.toString() + v.toString();

        // apply getAndAccumulate()
        int value = ref.getAndAccumulate(x, add);

        // print AtomicReference
        System.out.println(
            "The AtomicReference previous value: "
            + value);
        System.out.println(
            "The AtomicReference new value: "
            + ref.get());
    }
}

Output:

Program 2:

Java

// Java program to demonstrate
// AtomicReference.getAndAccumulate() method

import java.util.concurrent.atomic.*;
import java.util.function.BinaryOperator;

public class GFG {
    public static void main(String args[])
    {
        // AtomicReference with value
        AtomicReference<String> ref
            = new AtomicReference<String>("GFG ");

        // Value to apply getAndAccumulate
        String x = "Welcome";

        // Declaring the accumulatorFunction
        // applying function to add value as string
        BinaryOperator add
            = (u, v) -> v + " to " + u;

        // apply getAndAccumulate()
        String previousValue
            = ref.getAndAccumulate(x, add);

        // print AtomicReference
        System.out.println(
            "The AtomicReference previous value: "
            + previousValue);
    }
}