Java Program to Calculate the Power of a Number

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

class Main {
  public static void main(String[] args) {

    int base = 3, exponent = 4;

    long result = 1;

    while (exponent != 0) {
      result *= base;
      --exponent;
    }

    System.out.println("Answer = " + result);
  }
}

Output

Answer = 81

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

Using the while loop, we keep on multiplying the result by base until the 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 the power of a number using a for loop

class Main {
  public static void main(String[] args) {

    int base = 3, exponent = 4;

    long result = 1;

    for (; exponent != 0; --exponent) {
      result *= base;
    }

    System.out.println("Answer = " + result);
  }
}

Output

Answer = 81

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

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

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

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

class Main {
  public static void main(String[] args) {

    int base = 3, exponent = -4;
    double result = Math.pow(base, exponent);

    System.out.println("Answer = " + result);
  }
}

Output

Answer = 0.012345679012345678

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

We can also compute the power of a negative number using the pow() method.

Example 4: Compute Power of Negative Number

class Main {
  public static void main(String[] args) {

    // negative number
    int base = -3, exponent = 2;

    double result = Math.pow(base, exponent);
    System.out.println("Answer = " + result);
  }
}

Output

Answer = 9.0

Here, we have used the pow() method to compute the power of a negative number -3.