In this example, we will learn to calculate the execution time of normal methods and recursive methods in Java.
Example 1: Java Program to calculate the method execution time
class Main { // create a method public void display() { System.out.println("Calculating Method execution time:"); } // main method public static void main(String[] args) { // create an object of the Main class Main obj = new Main(); // get the start time long start = System.nanoTime(); // call the method obj.display(); // get the end time long end = System.nanoTime(); // execution time long execution = end - start; System.out.println("Execution time: " + execution + " nanoseconds"); } }
Output
Calculating Method execution time: Execution time: 656100 nanoseconds
In the above example, we have created a method named display(). The method prints a statement to the console. The program calculates the execution time of the method display().
Here, we have used the method nanoTime() of the System class. The nanoTime() method returns the current value of the running JVM in nanoseconds.
Example 2: Calculate the execution time of Recursive method
class Main { // create a recursive method public int factorial( int n ) { if (n != 0) // termination condition return n * factorial(n-1); // recursive call else return 1; } // main method public static void main(String[] args) { // create object of Main class Main obj = new Main(); // get the start time long start = System.nanoTime(); // call the method obj.factorial(128); // get the end time long end = System.nanoTime(); // execution time in seconds long execution = (end - start); System.out.println("Execution time of Recursive Method is"); System.out.println(execution + " nanoseconds"); } }
Output
Execution time of Recursive Method is 18600 nanoseconds
In the above example, we are calculating the execution time of recursive method named factorial().
