How to make the method run() of class NoThreadSafe thread-safe in Java

Method1.java

public class Method1 {
/*
Adding synchronized to this method will makes it thread-safe. 
When synchronized is added to a static method, the Class object is the object which is locked.
*/
  public static void main(String[] args) throws InterruptedException {

		ProcessingThreadS pt = new ProcessingThreadS();

		Thread t1 = new Thread(pt, "t1");

		t1.start();

		Thread t2 = new Thread(pt, "t2");

		t2.start();

		// wait for threads to finish processing

		t1.join();

		t2.join();

		System.out.println("Processing count=" + pt.getCount());

	}

}

class ProcessingThreadS implements Runnable {

	private int count;

	@Override

	public void run() {
		
		for (int i = 1; i < 5; i++) {
			processSomething(i);
			synchronized(this){
				this.count++;
			}			
		}
	}
	
	public synchronized int getCount() {
		return this.count;
    }

	private void processSomething(int i) {

		// processing some job

		try {

			Thread.sleep(i * 1000);

		} catch (InterruptedException e) {

			e.printStackTrace();

		}

	}
}

Method2.java

public class Method2 {
/*
We can make count++ atomic by using AtomicInteger from the package "java.util.concurrent.atomic"
*/
	public static void main(String[] args) throws InterruptedException {

		ProcessingThreadS2 pt = new ProcessingThreadS2();

		Thread t1 = new Thread(pt, "t1");

		t1.start();

		Thread t2 = new Thread(pt, "t2");

		t2.start();

		// wait for threads to finish processing

		t1.join();

		t2.join();

		System.out.println("Processing count=" + pt.getCount());

	}

}

class ProcessingThreadS2 implements Runnable {
	private static AtomicInteger count = new AtomicInteger(0);

	@Override

	public void run() {
		
		for (int i = 1; i < 5; i++) {
			processSomething(i);
			count.getAndIncrement();		
		}
	}
	
	public int getCount() {
		return count.get();
    }

	private void processSomething(int i) {

		// processing some job

		try {

			Thread.sleep(i * 1000);

		} catch (InterruptedException e) {

			e.printStackTrace();

		}

	}
}

NoThreadSafe.java

public class NoThreadSafe {

	public static void main(String[] args) throws InterruptedException {

		ProcessingThread pt = new ProcessingThread();

		Thread t1 = new Thread(pt, "t1");

		t1.start();

		Thread t2 = new Thread(pt, "t2");

		t2.start();

		// wait for threads to finish processing

		t1.join();

		t2.join();

		System.out.println("Processing count=" + pt.getCount());

	}

}

class ProcessingThread implements Runnable {

	private int count;

	@Override

	public void run() {

		for (int i = 1; i < 5; i++) {

			processSomething(i);

			count++;

		}

	}

	public int getCount() {

		return this.count;

	}

	private void processSomething(int i) {

		// processing some job

		try {

			Thread.sleep(i * 1000);

		} catch (InterruptedException e) {

			e.printStackTrace();

		}

	}
}