/**
* statistic sth.
*
* <p>implement by subclass.
*
* @return statistic data
*/
protected String statistic() {
CPUUsage current = currentCPUUsage();
double usagePercent = current.usagePercent(_last);
double idlePercent = current.idlePercent(_last);
_last = current;
return String.format("%4.2f, %4.2f", usagePercent, idlePercent);
}
