[Java] 성능 테스트 코드(시간, 메모리)

간단 성능 테스트 코드 

long time = System.currentTimeMillis();

reportPerformanceFor("starting at", time);

className.Method() //테스트하려는 함수 호출
reportPerformanceFor("graph allocation", time);

System.out.println("\n" + "Paused: graph is still in memory (to check mem consumption).");
System.out.print("press enter to free memory and finish...");

try {
    System.in.read();
} catch (IOException e) {
    e.printStackTrace();
}

System.out.println("done.");

private static void reportPerformanceFor(String msg, long refTime)
{
        double time = (System.currentTimeMillis() - refTime) / 1000.0;
        double mem = usedMemory()
            / (1024.0 * 1024.0);
        mem = Math.round(mem * 100) / 100.0;
        System.out.println(msg + " (" + time + " sec, " + mem + "MB)");
}

private static long usedMemory()
{
        Runtime rt = Runtime.getRuntime();

        return rt.totalMemory() - rt.freeMemory();
}