Measuring time(in ms) for particular operation in java

public class TimeMeasure {
public static void main(String arg[])
{
long startOperation = System.currentTimeMillis();

// Some operation

long endOperation = System.currentTimeMillis();
long timeTaken = endOperation - startOperation;
//long timeTaken = System.currentTimeMillis()-startOperation;
System.out.println("Time taken = "+timeTaken+" ms");
}
}

Iterator Demo

// Demonstrate iterators.
import java.util.*;
class IteratorDemo {
public static void main(String args[]) {
// create an array list
ArrayList al = new ArrayList();
// add elements to the array list
al.add("C");
al.add("A");
al.add("E");
al.add("B");
al.add("D");
al.add("F");
// use iterator to display contents of al
System.out.print("Original contents of al: ");
Iterator itr = al.iterator();
while(itr.hasNext()) {

Object element = itr.next();
System.out.print(element + " ");

}
System.out.println();
// modify objects being iterated
ListIterator litr = al.listIterator();
while(litr.hasNext()) {

Object element = litr.next();
litr.set(element + "+");

}
System.out.print("Modified contents of al: ");
itr = al.iterator();
while(itr.hasNext()) {

Object element = itr.next();
System.out.print(element + " ");

}
System.out.println();
// now, display the list backwards
System.out.print("Modified list backwards: ");
while(litr.hasPrevious()) {

Object element = litr.previous();
System.out.print(element + " ");

}
System.out.println();
}
}