AtomicReferenceArray getAndUpdate() method in Java with Examples

Last Updated : 16 Apr, 2021

The getAndUpdate() method of a AtomicReferenceArray class is used to atomically updates which updates the current value of the AtomicReferenceArray by applying the specified updateFunction operation on the current value. It takes an object of updateFunction interface as its parameter and applies the operation specified in the object to the current value. It returns the previous value.
Syntax:

public final E 
  getAndUpdate(int i, 
    UnaryOperator<E> updateFunction)

Parameters: This method accepts:

index i to update the index value and
updateFunction which is a side-effect-free function.

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

Java

// Java program to demonstrate
// AtomicReferenceArray.getAndUpdate() method

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

public class GFG {
    public static void main(String args[])
    {
        // an array
        String a[]
            = { "GFG", "JS",
                "PYTHON", "JAVA" };

        // AtomicReferenceArray with array
        AtomicReferenceArray<String> array
            = new AtomicReferenceArray<>(a);

        // Print AtomicReferenceArray
        System.out.println(
            "The AtomicReferenceArray before update : "
            + array);

        // Index
        int index = 2;

        // Declaring the accumulatorFunction
        // applying function
        UnaryOperator add
            = (u) -> u.toString() + " and ML";

        // apply getAndUpdate()
        String value
            = array.getAndUpdate(index, add);

        // print AtomicReferenceArray
        System.out.println("previous value of index 2:"
                           + value);
        System.out.println("The AtomicReferenceArray "
                           + "after update: "
                           + array);
    }
}

Output:

Program 2:

Java

// Java program to demonstrate
// AtomicReferenceArray.getAndUpdate() method

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

public class GFG {
    public static void main(String args[])
    {
        // an array
        Integer a[] = { 213, 1234, 4543, 345 };

        // AtomicReferenceArray with array
        AtomicReferenceArray<Integer> array
            = new AtomicReferenceArray(a);

        // Print AtomicReferenceArray
        System.out.println(
            "The AtomicReferenceArray"
            + " before update : "
            + array);
        // Index
        int index = 2;

        // Declaring the accumulatorFunction
        // applying function
        UnaryOperator add
            = (u) -> Integer.parseInt(u.toString()) * 200;

        // apply getAndUpdate()
        int value = array.getAndUpdate(index, add);

        // print AtomicReferenceArray
        System.out.println("previous value of index 2:"
                           + value);
        System.out.println("updated value of index 2:"
                           + array.get(2));
        System.out.println("The AtomicReferenceArray "
                           + "after update: "
                           + array);
    }
}