9.6（秒錶）

package hello;

public class StopWatch {
public static void  main(String[] args) {
	int a[] = new int[1000000];
	StopWatch watch = new StopWatch();
	watch.start();
	for(int i = 0; i < 1000000; i++) {
		a[i] = (int)(1000000 * Math.random()); 
	}
    watch.stop();
    System.out.println(watch.getElapsedTime());
}
private long startTime, endTime;
public StopWatch() {
	
}
public StopWatch(long startTime, long endTime) {
	startTime = System.currentTimeMillis();
}
void start() {
	startTime = System.currentTimeMillis();
}
void stop() {
	endTime = System.currentTimeMillis();
}
long getElapsedTime() {
	return endTime - startTime;
}
}