程序执行时间

private static void demo2(){
    long start = System.currentTimeMillis();
    int temp = 0;
    for (int i=0;i<100000000;i++){
        temp++;
    }
    long end = System.currentTimeMillis();
    long time = end - start;
    System.out.println("temp="+temp);
    System.out.println("程序执行时间"+(time/1000)+"秒");
}