Test

Test.java

public class Test {

    private static int plusOne(int i) {
        return ++i;
    }


    private static long oneForMethod(int x, int times) {
        long start = System.nanoTime();
        for (int i = 0; i < times; i++) {
            x = plusOne(x);
            x = plusOne(x);
            x = plusOne(x);
        }
        long end = System.nanoTime();
        return end - start;
    }


    private static long threeForMethod(int x, int times) {
        long start = System.nanoTime();
        for (int i = 0; i < times; i++) {
            x = plusOne(x);
        }
        for (int i = 0; i < times; i++) {
            x = plusOne(x);
        }
        for (int i = 0; i < times; i++) {
            x = plusOne(x);
        }
        long end = System.nanoTime();
        return end - start;
    }


    public static void main(String[] args) {
        test(false);
        test(false);
        test(false);
    }


    private static void test(boolean warmup) {
        long[] result = new long[6];
        int loops = 10000;
        int x = 0;
        for (int i = 0; i < loops; i++) {
            result[0] += threeForMethod(x, 10000);
            result[1] += oneForMethod(x, 10000);
        }

        if (!warmup) {
            System.out.println(result[0]);
            System.out.println(result[1]);
        }
    }

}

加上参数 -XX:+PrintCompilation