gistfile1.java

public class Bench {
    public static void main(String[] args) {
        double res;
        long start;
        int numVals = 1000000;
        
        System.out.println("Warming up");
        start = System.nanoTime();
        res = bar(new double[10000], 5000);
        System.out.println("Done. " + ((System.nanoTime() - start) / 1000000) + " ms (" + res + ")");
        
        System.out.println("Starting benchmark");
        start = System.nanoTime();
        res = bar(new double[numVals], 10000);
        System.out.println("Done. " + ((System.nanoTime() - start) / 1000000) + " ms (" + res + ")");
    }

    static double bar(double[] vals, int repeats) {
        for (int i = 0; i < repeats; i++)
            foo(vals);
        return vals[vals.length - 1]; // don't optimize away
    }
    
    static void foo(double[] vals) {
        for (int i = 0; i < vals.length; i++) {
            double x = i;
            vals[i] = Math.sqrt(x * x + 123.4);
        }
    }
}