ArrayList객체의 접근비용( The access cost of ArrayList Object )

package iteratorVSarray;
import java.util.ArrayList;
import java.util.Iterator;

import kr.ac.kyungnam.dblab.*;

public class Test {

        /**
         * @param args
         */
        public static void perform(Object o) {

        }
        public static void main(String[] args) {
                /*
                 * First, invoke all of the Benchmark class' method.
                 * Because of the character of static method's which is being loaded when class is loading.  
                 */
                Benchmark.start();
                Benchmark.finish();
                Benchmark.result();

                /*
                 * Make 1000000 Integer ArrayList Object
                 * The index number of ArrayList al is the same as the value
                 * 
                 * and check the creation Time.
                 */
                Benchmark.start();
                ArrayList al = new ArrayList();
                for(int i = 0; i < 1000000; i++) {
                        al.add( new Integer(i) );
                }
                Benchmark.finish();
                System.out.println("create Sample 1000000 Arraylist Data :" + Benchmark.result() + "ms");
                System.out.println();
                /*
                 * Check Iterator creation time
                 */
                Benchmark.start();
                Iterator it = al.iterator();
                Benchmark.finish();
                System.out.println("getting iterator : " + Benchmark.result() + "ms" );



                Benchmark.start();
                for(; it.hasNext(); )
                        perform(it.next());
                Benchmark.finish();
                System.out.println("iteration time: " + Benchmark.result()+ "ms");


                System.out.println();
                Benchmark.start();
                for(int i = 0 ; i < al.size() ; i++) {
                        perform(al.get(i));
                }
                Benchmark.finish();
                System.out.println("Arraylist's get(n) method:" + Benchmark.result() + "ms");
                System.out.println();


                Benchmark.start();
                Integer[] iv = new Integer[al.size()];
                iv = (Integer[])al.toArray(iv);
                Benchmark.finish();
                System.out.println("convert ArrayList type to Integer[] :" + Benchmark.result() + "ms");

                Benchmark.start();
                Object[] ov = al.toArray();
                Benchmark.finish();
                System.out.println("convert ArrayList type to Object[] :" + Benchmark.result() + "ms");


                Benchmark.start();
                for(int i = 0 ; i < iv.length ; i++) {
                        perform(iv[i]);
                }
                Benchmark.finish();
                System.out.println("getting Integer[]'s all element:" + Benchmark.result() + "ms" );


        }

}

결과