What is the relative performance difference of if/else versus switch statement in Java?

Question

Worrying about my web application\'s performances, I am wondering which of \"if/else\" or switch statement is better regarding performance?

Answer 1

Use switch!

I hate to maintain if-else-blocks! Have a test:

public class SpeedTestSwitch
{
    private static void do1(int loop)
    {
        int temp = 0;
        for (; loop > 0; --loop)
        {
            int r = (int) (Math.random() * 10);
            switch (r)
            {
                case 0:
                    temp = 9;
                    break;
                case 1:
                    temp = 8;
                    break;
                case 2:
                    temp = 7;
                    break;
                case 3:
                    temp = 6;
                    break;
                case 4:
                    temp = 5;
                    break;
                case 5:
                    temp = 4;
                    break;
                case 6:
                    temp = 3;
                    break;
                case 7:
                    temp = 2;
                    break;
                case 8:
                    temp = 1;
                    break;
                case 9:
                    temp = 0;
                    break;
            }
        }
        System.out.println("ignore: " + temp);
    }

    private static void do2(int loop)
    {
        int temp = 0;
        for (; loop > 0; --loop)
        {
            int r = (int) (Math.random() * 10);
            if (r == 0)
                temp = 9;
            else
                if (r == 1)
                    temp = 8;
                else
                    if (r == 2)
                        temp = 7;
                    else
                        if (r == 3)
                            temp = 6;
                        else
                            if (r == 4)
                                temp = 5;
                            else
                                if (r == 5)
                                    temp = 4;
                                else
                                    if (r == 6)
                                        temp = 3;
                                    else
                                        if (r == 7)
                                            temp = 2;
                                        else
                                            if (r == 8)
                                                temp = 1;
                                            else
                                                if (r == 9)
                                                    temp = 0;
        }
        System.out.println("ignore: " + temp);
    }

    public static void main(String[] args)
    {
        long time;
        int loop = 1 * 100 * 1000 * 1000;
        System.out.println("warming up...");
        do1(loop / 100);
        do2(loop / 100);

        System.out.println("start");

        // run 1
        System.out.println("switch:");
        time = System.currentTimeMillis();
        do1(loop);
        System.out.println(" -> time needed: " + (System.currentTimeMillis() - time));

        // run 2
        System.out.println("if/else:");
        time = System.currentTimeMillis();
        do2(loop);
        System.out.println(" -> time needed: " + (System.currentTimeMillis() - time));
    }
}

My C# standard code for benchmarking