Java concurrent test. (synchronized, AtomicInteger)

Java concurrent test. (synchronized, AtomicInteger)

package test01;
import java.text.MessageFormat;
import java.util.concurrent.atomic.AtomicInteger;

public class ConcurrentTest {

    static final int CONCURRENT = 100;
    static final int LOOP = 100000;
    static int counter;
    static AtomicInteger aCounter;
    public static void main(String[] args) throws Exception {
        char mode = (args.length == 0)     ? 0 :
                    (args[0].equals("-l")) ? 'l' :
                    (args[0].equals("-i")) ? 'i' :
                                             1;
        if (mode == 1) {
            throw new IllegalArgumentException("-i or -l");
        }
        int expected = CONCURRENT * LOOP;
        counter = 0;
        aCounter = new AtomicInteger(0);
        Runnable ts = null;
        if (mode == 0) {
            System.out.println("unuse lock.");
            ts = new Runnable(){
                public void run(){
                    for (int j = 0; j < LOOP; j++) {
                        counter++;
                    }
                }
            };
        }
        else if (mode == 'l') {
            System.out.println("lock.");
            final Object o = new Object();
            ts = new Runnable(){
                public void run(){
                    for (int j = 0; j < LOOP; j++) {
                        synchronized (o) { counter++; }
                    }
                }
            };
        }
        else if (mode == 'i') {
            System.out.println("AtomicInteger.");
            ts = new Runnable(){
                public void run(){
                    for (int j = 0; j < LOOP; j++) {
                        aCounter.incrementAndGet();
                    }
                }
            };
        }

        Thread[] threads = new Thread[CONCURRENT];
        for (int i = 0; i < threads.length; ++i) {
            threads[i] = new Thread(ts);
        }
        long start = System.currentTimeMillis();
        for (int i = 0; i < threads.length; ++i) {
            threads[i].start();
        }
        for (int i = 0; i < threads.length; ++i) {
            threads[i].join();
        }
        long end = System.currentTimeMillis();
        if (counter != 0) {
            System.out.println(MessageFormat.format("counter : {0}", counter));
        }
        else {
            System.out.println(MessageFormat.format("seed    : {0}", aCounter.get()));
        }
        System.out.println(MessageFormat.format("expected: {0}", expected));
        System.out.println(MessageFormat.format("time: {0}(ms)", end - start));
    }
}