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

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