sum and array list java

To sum the elements of an ArrayList in Java, you can iterate over the elements of the list and add them together using a loop.

Here's an example of how to sum the elements of an ArrayList of Integer objects:

ArrayList<Integer> list = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5));
int sum = 0;
for (int i : list) {
    sum += i;
}
System.out.println(sum);  // prints 15

In this example, we're using a for-each loop to iterate over the elements of the list and add them to the sum variable. The output will be the sum of the elements of the list: 15.

You can also use the stream API introduced in Java 8 to sum the elements of an ArrayList. Here's an example of how to do this:

ArrayList<Integer> list = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5));
int sum = list.stream().mapToInt(i -> i).sum();
System.out.println(sum);  // prints 15

In this example, we're using the stream method to create a stream of Integer objects, the mapToInt method to convert the stream to an IntStream, and the sum method to sum the elements of the stream.

You can find more information about the stream API and examples of how to use it in the Java documentation.