Finding execution time for particular statement/method in java

Lets look at below program

  

public class ExecutionTimeDemo {
 public static void main(String args[]) {
  ExecutionTime excTime = new ExecutionTime();
  excTime.startTime();
  excTime.testMethod();
  excTime.executionTime("testMethod execution time :");
 }

 public static void testMethod() {
  System.out.println("testMethod");
 }
}

class ExecutionTime{
 private long startTime;
 private long endTime;

 public void startTime() {
  startTime = System.nanoTime();
 }

 private void stopTime() {
  endTime = System.nanoTime();
 }

 public void executionTime(String s) {
  stopTime();
  System.out.println(s + (endTime - startTime));
 }

 public void testMethod() {
  System.out.println("testMethod");
 }
}

output :
testMethod
testMethod execution time :194788

will display the execution time of testMethod.

In real time, if you want to check whether ArrayList or Vector fast, you can use above program as below

  

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Vector;



public class ExecutionTimeDemo {
 
 public static void main(String args[]) {

  ExecutionTimeDemo excDemo = new ExecutionTimeDemo();
  excDemo.arrayListAddAll();
  excDemo.vectorAddAll();
 }

  
     public void arrayListAddAll() {
      ExecutionTime excTime = new ExecutionTime(); 
         List<string> stringList = Arrays.asList("1","2","3","4");
         List<string> arrayList = new ArrayList<string>();

         excTime.startTime();
         arrayList.addAll(stringList);
         excTime.executionTime("Array List addAll() = ");
     }
     
     
     public void vectorAddAll(){
      ExecutionTime excTime = new ExecutionTime(); 
          List<string> stringList = Arrays.asList("1","2","3","4");
          excTime.startTime();
          Vector<string> vector = new Vector<string>();
          vector.addAll(stringList);
          excTime.executionTime("vector addAll() = "); 
     }
}


class ExecutionTime{
 private long startTime;
 private long endTime;

 public void startTime() {
  startTime = System.nanoTime();
 }

 private void stopTime() {
  endTime = System.nanoTime();
 }

 public void executionTime(String s) {
  stopTime();
  System.out.println(s + (endTime - startTime));
 }

 public void testMethod() {
  System.out.println("testMethod");
 }
}

output :
Array List addAll() = 18862
vector addAll() = 31181

so Arraylist is faster than Vector