時間戳效率比較

package now.start;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Calendar;
import java.util.Date;
import java.util.Scanner;
import java.util.StringTokenizer;

public class Main {
	
	public static void main(String[] args) throws IOException{
		main2();
	}
	
	public static void main2(){
		
		int loopCount = 1000 * 10000;
		
		long way0 = System.currentTimeMillis();
		
		testWay1(loopCount);
		
		long way1 = System.currentTimeMillis();
		
		System.out.println("way1:" + (way1 - way0));
		
		testWay2(loopCount);
		
		long way2 = System.currentTimeMillis();
		
		System.out.println("way2:" + (way2 - way1));
		
		testWay3(loopCount);
		
		long way3 = System.currentTimeMillis();
		
		System.out.println("way3:" + (way3 - way2));
		
	}
	
	public static void testWay1(int loopCount){
		
		for(int i = 0; i < loopCount; i ++){
			System.currentTimeMillis();
		}
		
	}
	
	public static void testWay2(int loopCount){
		
		for(int i = 0; i < loopCount; i ++){
			Calendar.getInstance().getTimeInMillis();
		}
		
	}
	
	public static void testWay3(int loopCount){
		
		for(int i = 0; i < loopCount; i ++){
			new Date().getTime();
		}
		
	}

}

執行結果：

way1:6
way2:5611
way3:265


way1:6
way2:5513
way3:212


way1:6
way2:5526
way3:213


way1:6
way2:5572
way3:214