Computer Science 210
Data Structures
Fall 2019, Siena College
Sum1ToNRec BlueJ Project
Click here to download a BlueJ project for Sum1ToNRec.
Sum1ToNRec Source Code
The Java source code for Sum1ToNRec is below. Click on a file name to download it.
/**
* Example Sum1ToNRec: computing a sum with a simple recursive method
*
* @author Jim Teresco, The College of Saint Rose, CSC 523, Summer 2014
* @version Fall 2019
*
*/
public class Sum1ToNRec {
/**
a recursive version of the sumNumbersTo method
computes 1 + 2 + ... + limit
@param limit the upper limit of the range of numbers to sum
@return the sum of the numbers from 1 to limit
*/
public static int sumNumbersTo(int limit) {
// first, we check for the base case
if (limit == 1) return 1;
// otherwise, we have to make a recursive method call to compute the
// sum of the first limit-1 numbers, then add in limit to get our answer
return sumNumbersTo(limit - 1) + limit;
}
/**
main method to test our method
@param args not used.
*/
public static void main(String[] args) {
// for this example, we will just print out a few of these sums
int firstSum = sumNumbersTo(10);
System.out.println("The sum of the numbers 1-10 is " + firstSum);
int secondSum = sumNumbersTo(82);
System.out.println("The sum of the numbers 1-82 is " + secondSum);
// we skip this case, since it leads to an error: a stack overflow!
// more on this later.
//int thirdSum = sumNumbersTo(96352);
//System.out.println("The sum of the numbers 1-96352 is " + thirdSum);
// or we can use this within a loop
for (int number = 1; number <= 9; number++) {
// and we can use the value as part of a printout or any other expression
// if we do not want or need to save it in a variable
System.out.println("The sum of the numbers 1-" + number +
" is " + sumNumbersTo(number));
}
}
}