I have lists that I need to iterate through. I was using the new foreach from Java 8. I found it to be much slower than older less elegant methods. I've read this stack discussion which focuses more on best practices rather than real world implementation. I understand that with the lambda there is additional overhead that stems from method passing, but I still don't understand the discrepancy between the first and third case and that has me thinking I could be using it wrong. Are there not yet implemented optimizations for the lambda or is there a better way I could be using them to get more performance? Below is a demonstrative sample and not my actual code.
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
public class Main {
public static void main(String[] args) {
List<Memes> memesList =
Arrays.asList(
new OldMemes(),
new TrendingMemes()
);
//----------------------------Benchmark
long start, end;
start = System.nanoTime();
System.out.format("for each started @%d\n", start);
//Old way.
for(Memes memes : memesList){
memes.showMeme();
}
//-----------------------------Benchmark
end = System.nanoTime();
System.out.println((end - start));
start = System.nanoTime();
System.out.format("for started @%d\n", start);
//Other way
for(Iterator<Memes> i = memesList.iterator(); i.hasNext(); ) {
i.next().showMeme();
}
//-----------------------------Benchmark
end = System.nanoTime();
System.out.println((end - start));
start = System.nanoTime();
System.out.format("for each lambda started @%d\n", start);
//New way.
memesList.forEach((memes) -> memes.showMeme());
//-----------------------------Benchmark
end = System.nanoTime();
System.out.println((end - start));
System.out.format("end @%d\n", end);
}
interface Memes {
public void showMeme();
}
static class OldMemes implements Memes {
@Override
public void showMeme() {
System.out.println("Id appetere senserit his, nonumes consulatu vel id.");
}
}
static class TrendingMemes implements Memes {
@Override
public void showMeme() {
System.out.println("Id appetere senserit his, nonumes consulatu vel id.");
}
}
}
