[JAVA] (조금 더 정확한)실행시간 확인, 측정하기(timer)

실행환경
Notebook	SAMSUNG NT550p5c-s61r
CPU	Intel Core i5-3210M 2.50GHz
Memory	8 GB
OS	Window 7 ultimate 64bit
Java	1.7.0_51
Android	SDK : 4.4.2 (KitKat) / 테스트기기 : Galaxy S3 4.3 (Jelly Bean)
WebServer	Apache Tomcat 7.0

코드 실행시간 확인하기

조금 더 정확한 측정 방법

public class TimerTest {
	public static void main(String[] args) {

		ExecTime timer = new ExecTime();
		timer.start();

		// code
		for (int i = 0; i < 100000000; i++) {

		}
		timer.stop();

		timer.printExecTime();
		System.out.println(timer.getRunTimeNano() / 1000000 + " ms");
		System.out.println(timer.getRunTimeNano() / 1000000 / 1000 + " sec");
	}

}

class ExecTime {
	private long start;
	private long stop;

	void start() {
		start = System.nanoTime();
	}

	void stop() {
		stop = System.nanoTime();
	}

	long getRunTimeNano() {
		return stop - start;
	}

	void printExecTime() {
		System.out.println(stop - start + " ns");
	}
}

방법1

class TimeTest1 {
	public static void main(String[] args) {

		long startTime = System.currentTimeMillis();

		// code

		long stopTime = System.currentTimeMillis();
		long runTime = stopTime - startTime;

		System.out.println(runTime);
	}
}

방법 2

public class Stopwatch {
	long start;
	long end;
	
	void start() {
		start = System.currentTimeMillis();
	}
	
	void stop() {
		end = System.currentTimeMillis();
	}
	
	String getRunTime(){
		return end - start + "";
	}
}

class TimeTest2 {
	public static void main(String[] args) {

		Stopwatch timer = new Stopwatch().start();

		// code

		timer.stop();

		System.out.println(timer.getRunTime());
	}
}