public class BBDifferencetest {
    static AtomicInteger testnum  = new AtomicInteger();

     public static void testStringBuilder() {
             final StringBuffer sb = new StringBuffer();

             Thread t1 = new Thread() {

                     @Override
                     public void run() {
                             for (int x = 0; x < 60; x++) {
                                     testnum .getAndIncrement();
                                     sb.append(testnum );
                                     sb.append(" ");
                             }
                     }
             };
             Thread t2 = new Thread() {

                     public void run() {

                             for (int x = 0; x < 60; x++) {
                                     testnum .getAndIncrement();
                                     sb.append(testnum );
                                     sb.append(" ");
                             }
                     }
             };
             t1.start();
             t2.start();

             try {
                     t1.join();
                     t2.join();
             } catch (InterruptedException e) {
                     e.printStackTrace();
             }

             System.out.println("Result string is: " + sb.toString());

        }

     public static void main(String args[]) {
             testStringBuilder();
     }
}