什么是获得经过时间并重置它的正确方法

Question

In my android program I am using two Calendar instances to get the elapsed time in my program, first I set a level starting time as follows:

level_Start_TimeCal = Calendar.getInstance();   

and in my thread I am calculating elapsed time as follows:

level_current_TimeCal = Calendar.getInstance();
gameTime = level_current_TimeCal.getTimeInMillis()- level_Start_TimeCal.getTimeInMillis();                      
dsecs = (gameTime / 1000)%60;
dminutes = (gameTime / (60 * 1000))%60;
dhours = (gameTime / (60 * 60 * 1000))%60;

Recently I came to read the following:

Calendar's getInstance method returns a Calendar object whose calendar fields have been initialized with the current date and time

I want to know if I am in right path?
Am I creating an object each time the thread running?
If yes is there any alternative to avoid creating unwanted objects and calculating elapsed time? Final question: at some point I want to reset the time in my restart method I reset it by just calling getInstance in my reset method as follows:

public void restart() {
 level_Start_TimeCal = Calendar.getInstance();
}

Is this the correct way to reset the Calendar?

Answer 1

The best way to calculate elapsed time is to use System.nanotime() .

long start = System.nanoTime();
//do something
long end = System.nanoTime();

//to get the elapsed time, you can use the TimeUnit utility methods:
long elapsedInNanos = end - start;
long elapsedInSeconds = TimeUnit.SECONDS.convert(elapsedInNanos, TimeUnit.NANOSECONDS);

Note that it is not a useful method to access absolute time.