如何使用System.currentTimeMillis（）以秒为单位测量时间跨度？

Question

如何转换System.currentTimeMillis();为秒？

long start6=System.currentTimeMillis();
System.out.println(counter.countPrimes(100000000)+" for "+start6);

控制台向我显示5761455 for 1307816001290。我看不清那是多少秒。

有什么帮助吗？

Answer 1

long start = System.currentTimeMillis();
counter.countPrimes(1000000);
long end = System.currentTimeMillis();

System.out.println("Took : " + ((end - start) / 1000));

更新

甚至更准确的解决方案是：

final long start = System.nanoTime();
counter.countPrimes(1000000);
final long end = System.nanoTime();

System.out.println("Took: " + ((end - start) / 1000000) + "ms");
System.out.println("Took: " + (end - start)/ 1000000000 + " seconds");