show the usage of synchronized block in java

main.java

public class main {
    public static void main(String[] args){
        new mainSynchronize();
    }
}

mainSynchronize.java

package synchronize;

public class mainSynchronize {
    final MathClass mathClass = new MathClass();
    public mainSynchronize(){
        Runnable r = new Runnable() {
            @Override
            public void run() {
                try{
                    mathClass.printNumbers(3);
                }catch (InterruptedException e){
                    e.printStackTrace();
                }
            }
        };
        new Thread(r,"ONE").start();
        new Thread(r,"TWO").start();
    }
}

MathClass.java

package synchronize;

public class MathClass {
    synchronized void printNumbers(int n) throws InterruptedException
    {
            for (int i=1; i<=n;i++){
                System.out.println(Thread.currentThread().getName() + "::" + i);
                Thread.sleep(500);
           }
    }
}