Why:current thread not owner?

Question

Here is my class:
public class TestThread extends Thread {
    /* (non-Javadoc)
     * @see java.lang.Thread#run()
    @Override
    public void run() {
        System.out.println("begin");
        Test.check();
        System.out.println("end");
public class Test {
    private static Integer s_count = 0;
    public static void check() {
        synchronized (s_count) {
            while (s_count > 0) {
                try {
                    s_count.wait();
                    System.out.println("notify");
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
     * @param args
     * @throws InterruptedException
    public static void main(String[] args) throws InterruptedException{
        for (int i = 0; i < 5; i++) {
            s_count++;
            TestThread tt = new TestThread();
            tt.start();
        for (int i = 0; i < 5; i++) {
            Thread.sleep(3000);
            System.out.println(i);
            synchronized (s_count) {
                s_count--;
                System.out.println("s_count is:"+s_count);
                if (s_count == 0) {
                    try {
                        s_count.notifyAll();
                    } catch (Exception e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                System.out.println("ssss");
}

Answer 1

you are incrementing an Integer member var, which means you are creating a new object each time, hence as each thread runs, it is using a variety of different object references. try separating the lock from the counter:
    private static final Object s_lock = new Object();
    private static int s_count = 0;
    synchronized(s_lock) {
      // do your work on s_count
    }