The Java.util.concurrent.atomic.AtomicLongArray.getAndUpdate() is an inbuilt method in Java that updates the value at any given index of the AtomicLongArray after applying a given update function on the value at that index. The method takes the index value of the AtomicLongArray and the update function as the parameters and updates the value at that index by applying the update function on that value. The function should be side-effect-free, since it may be re-applied when attempted updates fail due to contention among threads. The only difference between the getAndUpdate() and updateAndGet() function is that the former returns the value before the update and the latter returns the value after the update.
Syntax:
public final long getAndUpdate(int i, LongUnaryOperator updateFunction)
Parameters: The function accepts two parameters:
Return value: The function returns a long value which is the value after applying the specified update function.
Below programs illustrate the above method:
Program 1:
// Java program that demonstrates // the getAndUpdate() function import java.util.concurrent.atomic.AtomicLongArray;
import java.util.function.LongUnaryOperator;
public class GFG {
public static void main(String args[])
{
// Initializing an array
long a[] = { 1 , 2 , 3 , 4 , 5 };
// Initializing an AtomicLongArray with array a
AtomicLongArray arr = new AtomicLongArray(a);
// Displaying the AtomicLongArray
System.out.println( "The array : " + arr);
// Index where update is to be made
int idx = 3 ;
// Declaring the updateFunction
LongUnaryOperator squaredFunction = (l) -> l * l;
// Updating the value at idx
// applying updateFunction and
// storing the previous value
long prev = arr.getAndUpdate(idx, squaredFunction);
// Displaying the previous value
System.out.println( "The value before update"
+ " at index " + idx
+ " is " + prev);
// Displaying the AtomicLongArray
System.out.println( "The array after update : "
+ arr);
}
} |
The array : [1, 2, 3, 4, 5] The value before update at index 3 is 4 The array after update : [1, 2, 3, 16, 5]
Program 2:
// Java program that demonstrates // the getAndUpdate() function import java.util.concurrent.atomic.AtomicLongArray;
import java.util.function.LongUnaryOperator;
public class GFG {
public static void main(String args[])
{
// Initializing an array
long a[] = { 1 , 2 , 3 , 4 , 5 };
// Initializing an AtomicLongArray with array a
AtomicLongArray arr = new AtomicLongArray(a);
// Displaying the AtomicLongArray
System.out.println( "The array : " + arr);
// Index where update is to be made
int idx = 3 ;
// Declaring the updateFunction
LongUnaryOperator cubeFunction = (l) -> l * l * l;
// Updating the value at idx
// applying updateFunction and
// storing the previous value
long prev = arr.getAndUpdate(idx, cubeFunction);
// Displaying the previous value
System.out.println( "The value before update"
+ " at index " + idx
+ " is " + prev);
// Displaying the AtomicLongArray
System.out.println( "The array after update : "
+ arr);
}
} |
The array : [1, 2, 3, 4, 5] The value before update at index 3 is 4 The array after update : [1, 2, 3, 64, 5]