class Counter { private int count = 0; public synchronized void increment() { count++; System.out.println(" incremented count to " + count); } public synchronized void decrement() { count--; System.out.println(" decremented count to " + count); } public synchronized int getCount() { return count; } } class IncrementTask implements Runnable { private Counter counter; public IncrementTask(Counter counter) { this.counter = counter; } @Override public void run() { for (int i = 0; i < 10; i++) { counter.increment(); } } } class DecrementTask implements Runnable { private Counter counter; public DecrementTask(Counter counter) { this.counter = counter; } @Override public void run() { for (int i = 0; i < 10; i++) { counter.decrement(); } } } public class CounterTest { public static void main(String[] args) { Counter counter = new Counter(); Thread incrementThread = new Thread(new IncrementTask(counter)); Thread decrementThread = new Thread(new DecrementTask(counter)); incrementThread.start(); decrementThread.start(); System.out.println("Final count: " + counter.getCount()); } }