inbuild method to sum of an arraylist elements in java

To sum the elements of an ArrayList in Java, you can use a loop to iterate through the list and add each element to a running total, or you can use the stream() method and the reduce() method to perform the sum in a single statement.

Here's an example using a loop:

ArrayList<Integer> numbers = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5));

int sum = 0;
for (int num : numbers) {
    sum += num;
}

System.out.println(sum);  // Output: 15

And here's an example using stream() and reduce():

ArrayList<Integer> numbers = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5));

int sum = numbers.stream().reduce(0, Integer::sum);

System.out.println(sum);  // Output: 15

Both of these examples will calculate the sum of the elements in the numbers list and print the result to the console.