DM_NEXTINT_VIA_NEXTDOUBLE

Dm: Method uses the nextDouble method of Random to generate a random integer; using nextInt is more efficient
使用nextDouble去產生一個random integer,造成效能降低。

If r is a java.util.Random, you can generate a random number from 0 to n-1 using r.nextInt(n), rather than using (int)(r.nextDouble() * n).
用nextInt(n)取代(int)(r.nextDouble() * n)即可。

Before:

	private static void delay(){
		int d = (int)(Math.random()*1000);
		try {
			Thread.sleep(d);
		} catch (InterruptedException e) {
			// log..
		}
	}

After:

	private static void delay(){
		int d = r.nextInt(1000);
		try {
			Thread.sleep(d);
		} catch (InterruptedException e) {
			// log..
		}
	}

PS. Math.random()內也是會去產生Random物件去取得亂數值。