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How to measure elapsed time in Java?
In general, the elapsed time is the time from the starting point to ending point of an event. Following are various ways to find elapsed time in Java −
Using the currentTimeMillis() method
The currentTimeMillis() method returns the current time in milliseconds. To find the elapsed time for a method you can get the difference between time values before and after the execution of the desired method.
Example
public class Example {
public void test(){
int num = 0;
for(int i=0; i<=50; i++){
num =num+i;
System.out.print(num+", ");
}
}
public static void main(String args[]){
//Start time
long begin = System.currentTimeMillis();
//Starting the watch
new Example().test();
//End time
long end = System.currentTimeMillis();
long time = end-begin;
System.out.println();
System.out.println("Elapsed Time: "+time +" milli seconds");
}
}Output
0, 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, 66, 78, 91, 105, 120, 136, 153, 171, 190, 210, 231, 253, 276, 300, 325, 351, 378, 406, 435, 465, 496, 528, 561, 595, 630, 666, 703, 741, 780, 820, 861, 903, 946, 990, 1035, 1081, 1128, 1176, 1225, 1275, Elapsed Time: 4 milli seconds
Using the nanoTime() method
The nanoTime() method returns the current time in nano seconds. To find the elapsed time for a method you can get the difference between time values before and after the execution of the desired method.
Example
public class Example {
public void test(){
int num = 0;
for(int i=0; i<=50; i++){
num =num+i;
System.out.print(num+", ");
}
}
public static void main(String args[]){
//Start time
long begin = System.nanoTime();
//Starting the watch
new Example().test();
//End time
long end = System.nanoTime();
long time = end-begin;
System.out.println();
System.out.println("Elapsed Time: "+time);
}
}Output
0, 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, 66, 78, 91, 105, 120, 136, 153, 171, 190, 210, 231, 253, 276, 300, 325, 351, 378, 406, 435, 465, 496, 528, 561, 595, 630, 666, 703, 741, 780, 820, 861, 903, 946, 990, 1035, 1081, 1128, 1176, 1225, 1275, Elapsed Time: 1530200
Using the Instant class
The now() method of the Instant class returns the current time and the Duration.between() methods returns the difference between the given two time values to get the elapsed time retrieve the time values before and after the execution of the desired method and retrieve the duration using the Duration.between() method.
Example
import java.time.Duration;
import java.time.Instant;
public class Example {
public void test(){
int num = 0;
for(int i=0; i<=50; i++){
num =num+i;
System.out.print(num+", ");
}
}
public static void main(String args[]) {
//Starting time
Instant start = Instant.now();
new Example().test();
//End time
Instant end = Instant.now();
long time = Duration.between(start, end).toMillis();
System.out.println();
System.out.println(time+" Milli seconds");
}
}Output
0, 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, 66, 78, 91, 105, 120, 136, 153, 171, 190, 210, 231, 253, 276, 300, 325, 351, 378, 406, 435, 465, 496, 528, 561, 595, 630, 666, 703, 741, 780, 820, 861, 903, 946, 990, 1035, 1081, 1128, 1176, 1225, 1275, 3 Milli seconds
Using the StopWatch class
The Apache commons library provides a class known as Stopwatch to it provides the start() stop() and getTime() methods to find the time taken for the execution of a method.
Following is the maven file of this package −
<dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-lang3</artifactId> <version>3.7</version> </dependency>
Example
import org.apache.commons.lang3.time.StopWatch;
public class Example {
public void test(){
int num = 0;
for(int i=0; i<=50; i++){
num =num+i;
System.out.print(num+", ");
}
}
public static void main(String args[]) {
//Instantiating the StopWatch class
StopWatch obj = new StopWatch();
//Starting the watch
obj.start();
new Example().test();
//Stopping the watch
obj.stop();
System.out.println();
System.out.println("Elapsed Time: "+obj.getTime() +" milli seconds");
}
}Output
0, 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, 66, 78, 91, 105, 120, 136, 153, 171, 190, 210, 231, 253, 276, 300, 325, 351, 378, 406, 435, 465, 496, 528, 561, 595, 630, 666, 703, 741, 780, 820, 861, 903, 946, 990, 1035, 1081, 1128, 1176, 1225, 1275, Elapsed Time: 1 milli seconds
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