Specifying which Objects to pull out of a Vector

Question

I'm pulling certain objects out of a vector to play with them. My problem is that I only want certain ones. Inside the vector "neighborList when I getMooreNeighbors are objects other than Soldiers (there are Democrats, Monarchs, etc, etc). I only want to fiddle with the Soldiers. I'm getting an NPE when I get to the "get" method because I'm casting the objects as Soldiers when it's possible some aren't. What do I do? How do I only get the Soldiers out of the Vector?
{code}
     public void getMyNeighbor () {
          neighborList = new Vector();
          soldierNeighbors = new Vector();
          neighborList = world.getMooreNeighbors(x, y, false);
          for (int i = 0; i < neighborList.size(); i++){
               Soldier otherSoldier = (Soldier) neighborList.get (i);//NPE here
               otherSoldier.getMyColor();
               otherSoldier.getStrength();
          if (otherSoldier.getMyColor()!=this.getMyColor()){
               fight();
{code}

Answer 1

So I think I tracked down that NPE, but another one seems to have cropped up. Is there a better way to write this? I'm asking my soldier to compare his color with the other guy and fight him if they don't match.
     public void getMyNeighbor () {
          neighborList = new Vector();
          soldierNeighbors = new Vector();
          neighborList = world.getMooreNeighbors(x, y, false);
          for (int i = 0; i < neighborList.size(); i++){
               Object o = neighborList.get (i);
               if (o instanceof Soldier) {
                    Soldier otherSoldier = (Soldier)o;
                    otherSoldier.getMyColor();
                    otherSoldier.getStrength();
          if (otherSoldier.getMyColor()!=this.getMyColor()){//NPE here
               fight();
          }