# Java Tutorial: The Power Function

Java doesn't provide the power operator. (For example, “^” in `3^4`

). You have to use `java.lang.Math.pow(3,4)`

. That method returns type “double”.

import java.lang.Math; class T2 { public double square (int n) { return java.lang.Math.pow(n,2); } } class T1 { public static void main(String[] arg) { T2 x1 = new T2(); double m = x1.square(3); System.out.println(m); } }

In the above example, we defined 2 classes, T1, T2.

“T1” is the main class for this file. Save the file as `T1.java`

.

The “T2” class defines one method, the “square”. It takes a “integer” and returns a decimal number of type “double”. (“double” basically means a large decimal number.)

In the main class “T1”, the line:

T2 x1 = new T2();

It means: `x1`

is a variable, its type is `T2`

. The value of `x1`

is a new instance of `T2`

.

The line:

double m = x1.square(3);

Calls the “square” method of “x1”, and assign the result to “m”.

In Java, all numbers have a type. All method definition must declare a type for each of their parameter, and declare a type for the thing the method returns.