Synchronized threads in JAVA

How can I make thread 1 when it reaches 10 or more, go to thread 2 and when it finishes adding its 5 numbers it will return to thread 1 to continue its series in case it has not finished yet?

THREADS

package pruebahilos;

public class Hilos extends Thread {

    Monitor mon = null;

    public Hilos(String name, Monitor m) {
        super(name);
        mon = m;
    }

    @Override
    public void run() {
        mon.lanzar(getName());
    }
    Thread Hilo2 = new Thread("Hilo 2") {
        @Override
        public void run() {
            mon.lanzar2(getName());
        }
    };
}

MONITOR

package pruebahilos;

public class Monitor {

    public int sum = 0;

    public synchronized void lanzar(String hilo1) {
        try {
            for (int i = 0; i < 5; i++) {
                if (sum == 10) {
                    System.out.println("La suma dio como resultado 10");
                }

                int num = (int) (Math.random() * 10 + 1);
                System.out.println(hilo1 + " " + " Valor  " + (i + 1) + " Numero: " + num);

                this.sum = this.sum + num;
                System.out.println("Resultado: " + this.sum);
            }

            System.out.println("La suma de los numeros es: " + sum + "\n\n");
        } catch (Exception e) {
            System.out.println("Error en el hilo 1");
        }
    }

    public synchronized void lanzar2(String hilo2) {
        try {
            if (sum <= 10) {
                wait();
            } else {
                int res = 0;

                for (int i = 0; i < 5; i++) {
                    if (res == 10) {
                        System.out.println("El Hilo 2 sumo 10 primero.");
                    }

                    int num = (int) (Math.random() * 10 + 1);
                    System.out.println(hilo2 + " " + " Valor  " + (i + 1) + " Numero: " + num);
                    res = res + num;

                    System.out.println("Resultado: " + res);
                }

                System.out.println("La suma de los numeros es: " + res);
            }
        } catch (InterruptedException InterruptedException) {
            System.out.println("Error en el hilo 2");
        }
    }

}

TRIAL THREAD

package pruebahilos;
public class PruebaHilos {
    public static void main(String[] args) {
        Monitor mon = new Monitor();
        Hilos h1 = new Hilos("Hilo 1", mon);
        Hilos h2 = new Hilos(" ", mon);
        h1.start();
        h2.Hilo2.start();
    }
}