Main.java

public class Main {

    public static void main(String[] args) {
        Runnable runnable = new Runnable() {
            private Object obj = null;
            @Override
            public void run() {
                displayHash();
            }

            private void displayHash() {
                if (obj == null) {
                    obj = new Object();
                }
                System.out.println(obj.hashCode());
            }
        };

        for (int i = 0; i < 5; i++) {
            Thread thread = new Thread(runnable);
            thread.start();
        }
    }
}