Scratch.java

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

class Scratch {
    public static void main(String[] args) throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
        TestClass testClass = new TestClass();

        long time = System.currentTimeMillis();
        for (int i = 0; i < 10000000; i++) {
            testClass.getClass().getMethod("test").invoke(testClass);
        }
        System.out.println(System.currentTimeMillis()-time + "ms");

        time = System.currentTimeMillis();
        Method method = testClass.getClass().getMethod("test");
        for (int i = 0; i < 10000000; i++) {
            method.invoke(testClass);
        }
        System.out.println(System.currentTimeMillis() - time + "ms");
    }


    static class TestClass{
        private int a;
        public void test(){
            a++;
        }
    }
}