The getAndAccumulate() method of a AtomicReferenceArray class is used to atomically updates the element at index i of AtomicReferenceArray 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 at index i as its first argument, and the given update as the second argument.
Syntax:
public final E getAndAccumulate(int i, E x,
BinaryOperator<E> accumulatorFunction)
Parameters: This method accepts:
- i which is an index of AtomicReferenceArray to perform the operation 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 program to demonstrate// getAndAccumulate() 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<Integer> array            = new AtomicReferenceArray<>(a);          // Print AtomicReferenceArray        System.out.println(            "The AtomicReferenceArray before update: "            + array);          // Index and Value to apply getAndAccumulate        int index = 2;        int E = 3;          // Declaring the accumulatorFunction        // applying function        BinaryOperator add            = (u, v)            -> Integer.parseInt(                   u.toString())                   * Integer                         .parseInt(                             v.toString());          // apply getAndAccumulate()        int value            = array.getAndAccumulate(index, E, add);          // print AtomicReferenceArray        System.out.println(            "previous value of index 2:"            + value);        System.out.println(            "The AtomicReferenceArray after update: "            + array);    }} |
Output:
Program 2:
// Java program to demonstrate// getAndAccumulate() 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<String> array            = new AtomicReferenceArray<>(a);          // Print AtomicReferenceArray        System.out.println(            "The AtomicReferenceArray before update : "            + array);          // Index and Value to apply getAndAccumulate        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 getAndAccumulate()        String value            = array.getAndAccumulate(index, E, add);          // print AtomicReferenceArray        System.out.println(            "previous value of index 1:"            + value);        System.out.println(            "The AtomicReferenceArray after update: "            + array);    }} |
Output:
