nanotime,【Java基础】时间比较 currentTimeMillis 与 nanoTime_myt2000的博客-
最后更新 :2022-12-12 12:44:21
时间比较 currentTimeMillis 与 nanoTime
nanoTime()
返回的是 正在运行的 Java 虚拟机的高分辨率时间源的当前值,以纳秒为单位。
currentTimeMillis()
返回的是 当前时间与 UTC 1970 年 1 月 1 日午夜之间的差异,以毫秒为单位。
public class Elapsed {
public static void main(String[] args) {
long start, end;
System.out.println("Timing for loop from 0 to 100,000,000");
start = System.currentTimeMillis();
System.out.println("start currentTimeMillis: " + start);
for (long i=0; i<100000000L; i++);
end = System.currentTimeMillis();
System.out.println("end currentTimeMillis: " + end);
System.out.println("Elapsed time: " + (end - start));
System.out.println("Timing for loop from 0 to 100,000,000");
start = System.nanoTime();
System.out.println("nano nanoTime: " + start);
for (long i=0; i<100000000L; i++);
end = System.nanoTime();
System.out.println("end nanoTime: " + end);
System.out.println("Elapsed time: " + (end - start));
}
}
输出结果
Timing for loop from 0 to 100,000,000
start currentTimeMillis: 1653033370155
end currentTimeMillis: 1653033370186
Elapsed time: 31
Timing for loop from 0 to 100,000,000
nano nanoTime: 261630972426900
end nanoTime: 261631001267300
Elapsed time: 28840400 // 这里等于28.84 ms
nanoTime()
要比currentTimeMillis()
更加精准,但是currentTimeMillis()
转换成Date
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