Java code - threads blocking each other

I am new to multithreading. I am trying to write a program where I have two threads. One thread prints an odd number and then drops the monitor lock using wait () and similarly another thread prints an even number and gives up the lock after printing the number I have 4 classes

• Odd.java (print odd numbers between 1-100)
  
• Even.java (print an even number between 1-100)
  
• SomeMaths.java (has logic to print odd and even numbers)
  
• OEApp.java (Main class that starts threads)
  

Problem. My code works as expected most of the time if it prints numbers from 1 to 100 in order. And the thread in turn. But I noticed there is a bug. Sometimes the even thread gets the scheduled first and exits below the output

2    **********
1    ###############################

      

        
        
        
      

    

After that nothing is printed. It looks like a dead end situation. I can't figure out why. Please help me understand this.

public class SomeMaths {

    public synchronized void printOdd(){
        for( int i=1;i<=100;i++){
            if(i%2 !=0) {
                System.out.println(i + "       ###############################");
                try {
                    wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            notify();
        }
    }

    public synchronized void printEven(){
        for(int i=1;i<=100;i++){
            if(i%2 ==0){
                System.out.println(i +"    **********");
                try {
                    wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            notify();
        }
    }
  }

      

        
        
        
      

    

public class Odd implements Runnable {

    SomeMaths sm;

    public Odd(SomeMaths sm){
        this.sm = sm;
    }
    @Override
    public void run(){
       sm.printOdd();
    }
}

      

        
        
        
      

    

public class Even extends Thread {

    SomeMaths sm;

    public Even(SomeMaths sm){
        this.sm = sm;
    }

    @Override
    public void run(){
        sm.printEven();
    }
}

      

        
        
        
      

    

public class OEApp {

    public static void main(String[] args) {

        SomeMaths sm = new SomeMaths();

        Thread odd = new Thread(new Odd(sm));
        Thread even = new Thread(new Even(sm));

        odd.start();
        even.start();

        try {
            odd.join();
            even.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}