Java: Measure how long some code takes to execute in nanoseconds

Last update on May 12 2025 13:11:30 (UTC/GMT +8 hours)

Code Execution Time in Nanoseconds

Write a Java program to measure how long code executes in nanoseconds.

Pictorial Presentation:

Sample Solution:

Java Code:

import java.lang.*;

public class Exercise91 {
    public static void main(String[] args) {    
        long startTime = System.nanoTime(); 
        
        // Sample program: Display the first 10 natural numbers.
        int i;
        System.out.println("The first 10 natural numbers are:\n");
        for (i = 1; i <= 10; i++) {      
            System.out.println(i);
        }
        
        // Calculate the elapsed time in nanoseconds.
        long estimatedTime = System.nanoTime() - startTime;
        System.out.println("Estimated time (in nanoseconds) to get the first 10 natural numbers: " + estimatedTime);
    }
}

Sample Output:

The first 10 natural numbers are:                                      
                                                                       
1                                                                      
2                                                                      
3                                                                      
4                                                                      
5                                                                      
6                                                                      
7                                                                      
8                                                                      
9                                                                      
10                                                                     
Estimated time (in nanoseconds) to get the first 10 natural numbers: 29
1045

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Java program to measure the execution time of sorting an array using different sorting algorithms.
• Write a Java program to compare execution times between iterating a list using a for-loop, an iterator, and a stream.
• Write a Java program to measure the execution time of a recursive Fibonacci function vs an iterative Fibonacci function.
• Write a Java program to measure the execution time of reading a large file using different input methods.

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