java.lang.Long Time in nanoseconds. If nanoTime is less than zero, then the service treats it as zero.

java.lang.Long The difference between the current time in nanoseconds and nanoTime. If nanoTime is greater than the current nano time, the service returns zero.

String The difference between the current time in nanoseconds and nanoTime. The difference is expressed as a String, in this format:

[years] [days] [hours] [minutes] [seconds] [millisec] [microsec] <nanosec>

If nanoTime is greater than the current nano time, the service returns zero.