public class Tmp {
    static double test(Runnable runnable) {
        double start = System.currentTimeMillis();
        runnable.run();
        return (System.currentTimeMillis() - start) / 1000.0;
    }

    public static void main(String[] args) {
        final int n = 100000000;

        System.out.println(test(new Runnable() {
                public void run() {
                    for(int i = 0; i < n; i++) {
                        double x = Math.random();
                        //System.out.println(x);
                    }
                }
            }));

        System.out.println(test(new Runnable() {
                public void run() {
                    double x;
                    for(int i = 0; i < n; i++) {
                        x = Math.random();
                        //System.out.println(x);
                    }
                }}));
    }
}