AutobixingImpact

package so;

import java.util.HashMap;
import java.util.Map;

public class AutoBoxing {

    public static void main(String[] args) {
        long start, end;

        Map<Integer, Integer> map = new HashMap<Integer, Integer>();

        // Using autobixing
        int kP = 1;
        int vP = 2;
        int resultPrimitive = 0;
        start = System.currentTimeMillis();
        for (int i = 0; i < 1E9; i++) {
            map.put(kP, vP);
            resultPrimitive = map.get(kP);
        }
        end = System.currentTimeMillis();
        System.out.println("Time with autoboxing: " + (end - start)
                + " useless variable I don't want optimized away: "
                + resultPrimitive);

        // Against using only objects
        Integer kO = Integer.valueOf(1);
        Integer vO = Integer.valueOf(2);
        Integer resultObject = Integer.valueOf(0);
        start = System.currentTimeMillis();
        for (int i = 0; i < 1E9; i++) {
            map.put(kO, vO);
            resultObject = map.get(kO);
        }
        end = System.currentTimeMillis();
        System.out.println("Time with autoboxing: " + (end - start)
                + " useless variable I don't want optimized away: "
                + resultObject);

    }
}