Testing the performance hit of using different methods of running code.

Perm.java

import java.util.*;

public class Perm {
    public static void main(String[] args) throws Exception {
        Perm perm = new Perm();
        long start = System.currentTimeMillis();
        for (int i = 0; i < Integer.MAX_VALUE; i ++) {
            perm.run();
        }
        System.out.println("Normal method: " + (System.currentTimeMillis() - start) + "ms");

        perm = new Perm();
        start = System.currentTimeMillis();
        Run tmp = (Run) Perm.class.getField("onRun").get(perm);
        for (int i = 0; i < Integer.MAX_VALUE; i ++) {
            tmp.run();
        }
        System.out.println("Interface field: " + (System.currentTimeMillis() - start) + "ms");

        Runner runner = new Runner();
        start = System.currentTimeMillis();
        for (int i = 0; i < Short.MAX_VALUE; i ++) {
            Runner.class.getMethod("run").invoke(runner);
        }
        System.out.println("Reflection invoke: " + (System.currentTimeMillis() - start) + "ms");
    }

    public Run onRun = () -> { int i = 0; };

    public void run() {
        int i = 0;
    }

    static interface Run {
        void run();
    }

    static class Runner implements Run {
        @Override
        public void run() {
            int i = 0;
        }
    }
}

results.md

Normal method: 8ms
Interface field: 11ms
Reflection invoke: 85ms

---

Normal method: 8ms
Interface field: 10ms
Reflection invoke: 82ms

---

Normal method: 9ms
Interface field: 10ms
Reflection invoke: 84ms

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Average normal method: 8.333ms
Average interface field: 10.333ms
Average reflection invoke: 83.666ms