System.currentTimeMillis如何在短时间内返回不同长度的long?

我正在创建临时目录

Files.createTempDirectory(String.format("project-it-screenshots-%d",
        System.currentTimeMillis())).toFile();

我以为 long System.currentTimeMillis() 因为两个不同长度的返回值来自不同的世纪,所以它们的长度都是相同的。在每天多次调用该方法之后

project-it-screenshots-15343380422205011345585140911467
project-it-screenshots-15343381444485756307954062111474
project-it-screenshots-15343386111604255833362898885857
project-it-screenshots-15343388402055473274775132302475
project-it-screenshots-1534338974370463603854456850155
project-it-screenshots-15343390449093279576023746896269
project-it-screenshots-15343398036346426501075034038757
project-it-screenshots-15343399888498609875231360701639
project-it-screenshots-15343401211515574289310135012571
project-it-screenshots-15343405563586337945661543042110
project-it-screenshots-15343419027757787065954653813302
project-it-screenshots-15343425353682119990056938907868
project-it-screenshots-15343429571018010152043055630277
project-it-screenshots-15343431608662744493593200651167
project-it-screenshots-15343436122094379676346949668973
project-it-screenshots-15343442103124076542522856351947
project-it-screenshots-15343539846818150078805796257638
project-it-screenshots-15343555678106536264262565060437
project-it-screenshots-15343809068582300780873443756155
project-it-screenshots-15344378068483088975615680511653
project-it-screenshots-15344421866441533761733546877922

哪里 1534338974370463603854456850155 比其他数字短一位数。这似乎与剥夺领导权无关 0 0个 因为一些长度较大的数字有,而另一些没有。

0个 用填充到数字 String.format 只会稍微改变时间戳)。