private void createWeightCollection() {
   weightCollection = new RandomCollection<Integer>(worldObj.rand);
   weightCollection.add(WEIGHT_POP, ACTION_POP);
   weightCollection.add(WEIGHT_SPAWNMOB, ACTION_SPAWNMOB);
   weightCollection.add(WEIGHT_POTION, ACTION_POTION);
   weightCollection.add(WEIGHT_SPAWNITEM, ACTION_SPAWNITEM);
   weightCollection.add(WEIGHT_LIGHTNING, ACTION_LIGHTNING);
 }
 private void act() {
   int action = weightCollection.next();
   switch (action) {
     case ACTION_POP:
       pop();
       break;
     case ACTION_SPAWNMOB:
       spawnMob();
       break;
     case ACTION_POTION:
       potion();
       break;
     case ACTION_SPAWNITEM:
       spawnItem();
       break;
     case ACTION_LIGHTNING:
       spawnLightning();
       break;
   }
 }