How to use wait and notify in Java without IllegalMonitorStateException?

Question

I have 2 matrices and I need to multiply them and then print the results of each cell. As soon as one cell is ready I need to print it, but for example I need to print the [

Answer 1

To be able to call notify() you need to synchronize on the same object.

synchronized (someObject) {
    someObject.wait();
}

/* different thread / object */
synchronized (someObject) {
    someObject.notify();
}