final List list = new ArrayList();
for (int i = 0 ; i < 1000000 ; ++i) {
    list.add(i);
}

1. foreach

   final List forLoopCopy = new ArrayList();
   final long forLoopStartTime = System.currentTimeMillis();
   for (Integer item : list) {
       forLoopCopy.add(item);
   }
   final long forLoopElapsed = System.currentTimeMillis() - forLoopStartTime;
   System.out.println("for loop elapsed: " + forLoopElapsed);
   

2. for index

   final List forIndexCopy = new ArrayList();
   final long forIndexStartTime = System.currentTimeMillis();
   for (int i = 0 ; i < list.size() ; ++i) {
       forIndexCopy.add(list.get(i));
   }
   final long forIndexElapsed = System.currentTimeMillis() - forIndexStartTime;
   System.out.println("for index elapsed: " + forIndexElapsed);
   

3. Và stream

   final List streamCopy = new ArrayList();
   list.forEach(it -> streamCopy.add(it)); // warm up chương trình
   final long streamStartTime = System.currentTimeMillis();
   list.stream().forEach(it ->
       streamCopy.add(it)
   );
   final long streamElapsed = System.currentTimeMillis() - streamStartTime;
   System.out.println("stream elapsed: " + streamElapsed);
   

for loop elapsed: 16
for index elapsed: 15
stream elapsed: 41