AtomicLongArray getAndDecrement() method in Java with Examples

The Java.util.concurrent.atomic.AtomicLongArray.getAndDecrement() is an inbuilt method in Java that atomically decrements the value at a given index by one. This method takes the index value of the AtomicLongArray and returns the value present at that index and then decrements the value at that index. The function getAndDecrement() is similar to decrementAndGet() but the latter function returns the value after the decrement whereas the former returns the value before the decrement.

Syntax:

public final long getAndDecrement(int i)

Parameters: The function accepts a single parameter i which is the index where decrement by one operation is performed.

Return value: The function returns the value before the decrement operation at the index which is in long.

Below programs illustrate the above method:
Program 1:

// Java program that demonstrates
// the getAndDecrement() function

import java.util.concurrent.atomic.AtomicLongArray;

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 operation is performed
        int idx = 3;

        // Decrementing the value at
        // idx applying getAndDecrement
        // and storing previous value
        long prev = arr.getAndDecrement(idx);

        // The previous value at idx
        System.out.println("Value at index " + idx
                           + " before decrement is "
                           + prev);

        // Displaying the AtomicLongArray
        System.out.println("The array after decrement : "
                           + arr);
    }
}

Output:

The array : [1, 2, 3, 4, 5]
Value at index 3 before decrement is 4
The array after decrement : [1, 2, 3, 3, 5]

Program 2:

// Java program that demonstrates
// the getAndDecrement() function

import java.util.concurrent.atomic.AtomicLongArray;

public class GFG {
    public static void main(String args[])
    {
        // Initializing an array
        long a[] = { 10, 20, 30, 40, 50 };

        // Initializing an AtomicLongArray with array a
        AtomicLongArray arr = new AtomicLongArray(a);

        // Displaying the AtomicLongArray
        System.out.println("The array : " + arr);

        // Index where operation is performed
        int idx = 0;

        // Decrementing the value at
        // idx applying getAndDecrement
        // and storing previous value
        long prev = arr.getAndDecrement(idx);

        // The previous value at idx
        System.out.println("Value at index " + idx
                           + " before decrement is "
                           + prev);

        // Displaying the AtomicLongArray
        System.out.println("The array after decrement : "
                           + arr);
    }
}

Output:

The array : [10, 20, 30, 40, 50]
Value at index 0 before decrement is 10
The array after decrement : [9, 20, 30, 40, 50]

Reference: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/atomic/AtomicLongArray.html#getAndDecrement-int-