看到了几种循环测试效率的测试

     不用多说看代码 一目了然，代码不是我写的，是复制其他博客上的，与其独乐乐，不如众乐乐。
     import java.util.ArrayList;
import java.util.Collections;
import com.google.common.base.Stopwatch;
import java.util.Iterator;

public class Benchmark {
    public static void main(final java.lang.String[] args) {
        final int SIZE = Integer.MAX_VALUE / 32;
        System.out.printf("loop times: %d%n",SIZE);
        Stopwatch stopwatch = new Stopwatch().start();
        ArrayList<String> list = new ArrayList<>(SIZE);
        for (int i = 0; i < SIZE; i++) {
            list.add(" ");
        }
        long millis = stopwatch.elapsedMillis();
        System.out.printf("init took: %dms%n",millis);

        StringBuilder builder = new StringBuilder(SIZE);
        stopwatch = stopwatch.reset().start();
        for (int i = 0; i < SIZE; i++) {
            builder.append(list.get(i));
        }
        millis = stopwatch.elapsedMillis();
        System.out.printf("for loop took: %dms%n",millis);

        builder.delete(0,SIZE);
        stopwatch = stopwatch.reset().start();
        for (String v : list) {
            builder.append(v);
        }
        millis = stopwatch.elapsedMillis();
        System.out.printf("foreach took: %dms%n",millis);

        builder.delete(0,SIZE);
        stopwatch = stopwatch.reset().start();
        for (Iterator<String> iter = list.iterator(); iter.hasNext(); ) {
            builder.append(iter.next());
        }
        millis = stopwatch.elapsedMillis();
        System.out.printf("iterator loop took: %dms%n",millis);
    }
}

Oracle JDK 7u1

Java code
java -Xmx512m  -cp .:guava-10.0.jar Benchmark
loop times: 67108863
init took: 1601ms
for loop took: 3688ms
foreach took: 4766ms
iterator loop took: 4546ms

Java code
java -server -Xmx512m  -cp .:guava-10.0.jar Benchmark
loop times: 67108863
init took: 1129ms
for loop took: 3876ms
foreach took: 3491ms
foreach loop took: 4318ms

大神如果你看到这代码是写，不好意思啊。希望不是版权盗用啊   后面是两种测试结果，