Sum2

// This program uses a function to sum up the sequence
// of integers from 1 to 10
class Sum2 {

    public static void main(String[] args) {
	System.out.println( sum(10) );
    }

    //Sum up integers from 1 to N.
    // assume N > 0
    static int sum(int N) {
	int total=0;

	for (int i=1; i<=10; i++) {
	    total += i;
	}
	return total;
    }
}
This version has a number of small changes that make it look a little more like a real Java programmer would write it.
  1. Rather than creating a variable to hold the value returned by the sum() function, I just put the call to sum directly into the call to System.out.println().
  2. Down in the sum function, I used the increment operator, '++'. Adding '1' to a variable (incrementing it) is so common, many languages (C/C++, Java, Perl, Python, PHP to name a few) use this operator as a sort of abbreviation. Using this operator allows me to write i=i+1 as simply i++.
  3. Another operator was introduced to allow incrementing a variable by a number other than one. This is what '+=' does. This let me write total=total+i as total+=i. Similarly, there are a number of other operators that do this kind of thing like '*=' which means multiply the variable on the left side by the number on the right side so that something like a = a * 3 would be written a *= 3.