Sure, here's a Java program to calculate the sum of natural numbers:

public class SumOfNaturalNumbers {
    public static void main(String[] args) {
        int n = 10;
        int sum = 0;
        
        for (int i = 1; i <= n; i++) {
            sum += i;
        }
        
        System.out.println("Sum of natural numbers from 1 to " + n + " = " + sum);
    }
}

In this program, we first define an integer n to represent the upper limit of the natural numbers to sum. We then initialize an integer sum to 0.

We use a for loop to iterate from 1 to n and add each number to sum. Finally, we print out the sum of the natural numbers from 1 to n.

Note that the formula for the sum of the natural numbers from 1 to n is:

sum = (n * (n + 1)) / 2

This formula can be used to calculate the sum of natural numbers without using a loop, which is more efficient for large values of n.