Methods in Java

Methods are not to be confused with functions. As you might know the term functions, let's elaborate on what methods are. Methods are functions, bound to a class. As everything in Java is bound to a class, we almost only speak of methods here.

static int timesTwo(int x) {
    return x * 2;
}

public static void main(String args[]) {
    System.out.println(timesTwo(2)); // 4
}

Methods can be used in code before they are declared - as Java code is compiled, this is no problem.

Method overloading

One can declare multiple methods with the same name. This does not lead to an error as Java detects which function you want to call depending on the data type passed into the call.

static int timesTwo(int x) {
    return x * 2;
}
static double timesTwo(double x) {
    return x * 2;
}

Recursion

A Java method can be recursive, therefore, call itself.

public int fibonacci(int n)  {
    if(n == 0)
        return 0;
    else if(n == 1)
      return 1;
   else
      return fibonacci(n - 1) + fibonacci(n - 2);
}