i++ 与 i.getAndIncrement() 性能比较

import java.util.concurrent.atomic.AtomicInteger;

public class IncrementCompare {
    public static void main(String[] args) {
        int N = 1000000000;
        int i = 0;
        AtomicInteger j = new AtomicInteger(0);

        Long time_1 = System.currentTimeMillis();
        for (int k = 0; k < N; k++) {
            i++;
        }
        Long time_2 = System.currentTimeMillis();
        System.out.println("i=" + i);
        System.out.println(time_2-time_1 + "ms");


        for (int m = 0; m < N; m++) {
            j.getAndIncrement();
        }
        System.out.println("j=" + j);
        Long time_3 = System.currentTimeMillis();

        System.out.println(time_3-time_2 + "ms");


    }
}

进行 10亿次操作，速度大概差了1000倍