Example 1: Calculate power of a number using a while loop

1. public class Power {
3. public static void main(String[] args) {
5. int base = 3, exponent = 4;
7. long result = 1;
9. while (exponent != 0)
10. {
11. result *= base;
12. --exponent;
13. }
15. System.out.println("Answer = " + result);
16. }
17. }

When you run the program, the output will be:

Answer = 81

In this program, base and exponent are assigned values 3 and 4 respectively.

Using the while loop, we keep on multiplying result by base until exponent becomes zero.

In this case, we multiply result by base 4 times in total, so result = 1 * 3 * 3 * 3 * 3 = 81.

Example 2: Calculate power of a number using a for loop

1. public class Power {
3. public static void main(String[] args) {
5. int base = 3, exponent = 4;
7. long result = 1;
9. for (;exponent != 0; --exponent)
10. {
11. result *= base;
12. }
14. System.out.println("Answer = " + result);
15. }
16. }

When you run the program, the output will be:

Answer = 81

Here, instead of using a while loop, we’ve used a for loop.

After each iteration, exponent is decremented by 1, and result is multiplied by base exponent number of times.

Both programs above doesn’t work if you have a negative exponent. For that, you need to use pow() function in Java standard library.

Example 3: Calculate the power of a number using pow() function

1. public class Power {
3. public static void main(String[] args) {
5. int base = 3, exponent = -4;
6. double result = Math.pow(base, exponent);
8. System.out.println("Answer = " + result);
9. }
10. }

When you run the program, the output will be:

Answer = 0.012345679012345678

In this program, we use Java’s Math.pow() function to calculate the power of the given base.