# Do Power in Java

This tutorial introduces how to do power operation in Java and lists some example codes to understand the topic.

To raise a number to a power in Java, we can use the `pow()` method of the `Math` class or own custom code that uses loop or recursion technique. Let’s see some examples.

## Raise a Number to a Power Using the `pow()` Method in Java

The `pow()` method belongs to the `Math` class in Java used to generate a number of the given power. It is a simple and straightforward approach because `pow()` is a built-in method that reduces the effort to write custom code. See the example below.

``````public class SimpleTesting{
public static void main(String[] args) {
double a = 20;
double power = 2;
double result = Math.pow(a, power);
System.out.println(a+" power of "+power + " = "+result);
}
}
``````

Output:

``````20.0 power of 2.0 = 400.0
``````

## Raise a Number to Power Using the `while` Loop in Java

If you don’t want to use the built-in `pow()` method, then use the custom code below. We use a `while` loop inside this code to generate a number to a power. See the example below.

``````public class SimpleTesting{
public static void main(String[] args) {
double a = 20;
double power = 2;
double result = 1;
double temp = power;

while (temp != 0)
{
result *= a;
--temp;
}
System.out.println(a+" power of "+power + " = "+result);
}
}
``````

Output:

``````20.0 power of 2.0 = 400.0
``````

## Raise a Number to Power Using the `for` Loop in Java

If you don’t want to use the built-in `pow()` method, use the custom code below. We use the `for` loop inside this code to generate a number to a power. See the example below.

``````public class SimpleTesting{
public static void main(String[] args) {
double a = 20;
double power = 2;
double result = 1;
double temp = power;

for (;temp != 0; --temp)
{
result *= a;
}
System.out.println(a+" power of "+power + " = "+result);
}
}
``````

Output:

``````20.0 power of 2.0 = 400.0
``````

## Raise a Number to a Power Using the `recursion` in Java

This is another approach where we can use `recursion` to raise a number to a power in Java. Recursion is a technique in which a function calls itself repeatedly until the base condition meets. Here, we create a recursion method, `pow()`. See the example below.

``````public class SimpleTesting{
static double result = 1;
static void  pow(double n,double p)
{
if(p<=0)
{
return;
}
else if(n==0 && p>=1)
{
result=0;
return;
}
else
result=result*n;
pow(n,p-1);
}
public static void main(String[] args) {
double a = 20;
double power = 2;
pow(a,power);
System.out.println(a+" power of "+power + " = "+result);
}
}
``````

Output:

``````20.0 power of 2.0 = 400.0
``````

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