java - Variable does not increment in probability program -

i have 3 classes. super class probability, subclass eating , runner class person.

the goal methods "triggered" when conditions met in loop. eating (method dox) increase variable weight. once weight greater 120, probability (int px) of dox being called decreases , probability (py) of exercising increases until weight drops below threshold.

however int px never decreases. why this? below decrease probability methods , trigger calls them.

public void trigger() {     if (weight >= 120)     {         dprob(px);         dprob(pz);         iprob(py);     }     if (weight <= 80)     {         dprob(py);         iprob(px);         iprob(pz);     }   public void dprob(int p) {     p -= 5; }  public void iprob (int p) {     p += 5; }  

p local variable method dprob, , it's different variable p in iprob. meaning px, pz , py not affected (java passes by value, always).

when enter method, temporary variable created, , destroyed exit it.

you should make p class member (read more here), or let methods return result, , assign caller, or directly modify px, py , pz.