Program to calculate execution time of code/ functional block in java

• Given the code or functional block of program , we would like to find elapsed time, to execute the code block.
• We can find the execution time in milliseconds.  We can also find the execution time in nano seconds (if we need more precision).
  • Note down current clock time (milliseconds or nanoseconds)
    • Mark it as startTime
  • Execute the block of code
    • Whose execution time, we would like to measure
  • Note down the time at end of code block (milliseconds or nanoseconds)
    • Mark it as endTime
  • Find out the difference = endTime – startTime
    • We got the desired execution time

Program – calculate execution time of code/ functional block in java.

package org.learn;

class Employee {
 public String name;
 public int age;

 public Employee(String name, int age) {
  this.name = name;
  this.age = age;
 }

 public String toString() {
  return "[User: " + name + " " + age +  "]";
 }
}

public class ExecutionTime { 

 public static void main(String[] args) throws InterruptedException {
  //Example 1 : Time to 1000 create object using mills
  long startTime = System.currentTimeMillis();
  for (int index = 0 ; index < 1000; index++) {
   new Employee("name "+index,index);   
   Thread.sleep(10);
  }
  long endTime = System.currentTimeMillis();
  System.out.printf("1. Execution time to create 1000 objects: %d ms\n" ,
         (endTime-startTime));
  
  //Example 2 using nano second 
  startTime = System.nanoTime();
  for (int index = 0 ; index < 1000; index++) {
   new Employee("name "+index,index);   
   Thread.sleep(10);
  }
  endTime = System.nanoTime();
  System.out.printf("2. Execution time to create 1000 objects: %d ns" ,
         (endTime-startTime));
 }
}

Output – find execution time of code/functional block in java

1. Execution time to create 1000 objects: 10221 ms
2. Execution time to create 1000 objects: 10219039717 ns