AtomicReferenceArray updateAndGet() method in Java with Examples

The updateAndGet() 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 V updateAndGet(
  UnaryOperator<V> 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 updateAndGet() method: 
Program 1:

Java

// Java program to demonstrate
// AtomicReferenceArray.updateAndGet() 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 updateAndGet()
        String value
            = array.updateAndGet(index, add);

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

Output:

Program 2:

Java

// Java program to demonstrate
// AtomicReferenceArray.updateAndGet() 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()) * 500;

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

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

Output:

References: https://docs.oracle.com/javase/10/docs/api/java/util/concurrent/atomic/AtomicReferenceArray.html#updateAndGet(java.util.function.UnaryOperator)