How to get around the ConcurrentModificationException in Java?

Question

This is for a personal project, I am trying to create a survival-like simulation using dinosaurs as agents.

The main part of the simulation is a do:while loop, and inside that do:while loop is 3 for:each loops (not nested) that run through three different ArrayLists. Each ArrayList is an array of objects, that each do different things.

Dinosaurs move around the field and can eat other Dinosaur objects, Grass objects, or Water objects. Neither Grass objects nor Water objects disappear after being eaten, however Dinosaur objects are removed from the dinosaurs ArrayList if they are eaten. Here's my relevant code:

for (Grass grass : grasses) {
    System.out.println(grass);
}

//simulation loop
do {
    for (Grass grass : grasses) {
        grass.timeToGrow();
    }
    for (Water water : waters) {

    }
    for (Dinosaur dinosaur : dinosaurs) {
        if(simulationLength % 3 == 0) { //dinosaurs lose 1 health and food every 3 turns
            dinosaur.addFood(-1);
            dinosaur.addWater(-1);
        }
        dinosaur.loseHealth();
        dinosaur.move(dinosaurs, grasses, waters);
        dinosaurs.add(dinosaur.timeToReproduce());
    }
    System.out.println("There are " + dinosaurs.size() + " dinosaurs left.");
    simulationLength -= 1;
    simulationTime += 1;
    //TODO update GUI
} while (simulationLength > 0);

System.out.println("¡THE SIMULATION IS DONE!");

dinosaur.move() moves each dinosaur in the ArrayList of dinosaurs. If a dinosaur is a carnivore and lands on another dinosaur it eats it, and the eaten dinosaur is removed from the list. dinosaur.timeToReproduce() returns a Dinosaur object if the dinosaur is supposed to use food and make another Dinosaur (that is added to the list of Dinosaurs) and null if not.

public void move(ArrayList<Dinosaur> dinosaurs, ArrayList<Grass> grasses, ArrayList<Water> waters) {
    Positioned food = getFoodSource(dinosaurs, grasses, waters);
    try { //to find food
        if(distanceTo(food) <= getSpeed()) {    //can move to food in one turn
            moveInRange(dinosaurs, grasses, waters);
        } else {                                //food is out of reach
            moveOutRange(dinosaurs, grasses, waters);
        }
    } catch (NullPointerException e) { //didn't find any food :(
        //TODO make the dino search for alternate food source
        //TODO make the dino wander if truly no food

        //not yet moving
        setxLoc(getxLoc());
        setyLoc(getyLoc());
    }
}

public void moveInRange(ArrayList<Dinosaur> dinosaurs, ArrayList<Grass> grasses, ArrayList<Water> waters) {
    Positioned food = getFoodSource(dinosaurs, grasses, waters);      //searching out target...

    int xLocFood = food.getxLoc();
    int yLocFood = food.getyLoc();

    this.setxLoc(xLocFood);
    this.setyLoc(yLocFood);

    switch (food.getName()) {
        case "grass":
            //grass just got eaten. it now has to regrow
            System.out.println(this + " just ate " + food + "!");
            grasses.get(grasses.indexOf(food)).setGrowthStage(1);
            this.addHealth(4);
            this.addFood(4);
            break;
        case "water":
            //you gots to do nothing. water doesn't go away
            System.out.println(this + " just drank " + food + "!");
            this.addHealth(2);
            this.addWater(4);
            break;
        case "dinosaur":
            //remove the dinosaur you just ate
            System.out.println(this + " just tried to eat " + food + "!");
            battle(dinosaurs.get(dinosaurs.indexOf(food)), dinosaurs);
            break;
    }
}

public void moveOutRange(ArrayList<Dinosaur> dinosaurs, ArrayList<Grass> grasses, ArrayList<Water> waters) {
    Positioned food = getFoodSource(dinosaurs, grasses, waters);      //searching out target...

    //if there is not a valid food source found then the next 2 lines will throw a NullPointerException
    int xLocFood = food.getxLoc();
    int yLocFood = food.getyLoc();

    int newXLoc;
    int newYLoc;
    double dx = xLocFood - getxLoc();   //total x distance to food
    double dy = yLocFood - getyLoc();   //total y distance to food
    double theta = Math.atan(dy / dx);      //θ = arctan(dy/dx)

    //rounding for accuracy
    newXLoc = (int) Math.round(getSpeed() * Math.cos(theta));   //x=speed*cos(θ)
    newYLoc = (int) Math.round(getSpeed() * Math.sin(theta));   //y=speed*sin(θ)

    setxLoc(getxLoc() + newXLoc);                           //newX = x+moveX
    setyLoc(getyLoc() + newYLoc);                           //newY = y+moveY
}

public void battle(Dinosaur dino, ArrayList<Dinosaur> dinosaurs) {
    //attack vs defense
    int dH = this.getAttack() - dino.getDefense();
    if(dH > 0) {        //dinosaur's attack is greater than the other guy's defense
        System.out.println("\t" + dino + " just lost " + dH + " health!");
        dino.addHealth(-dH);
        this.addFood(dino.curFood / 2);
        if(dino.getHealth() <= 0) {
            System.out.println("\t" + dino + " was just eaten!");
            for (int i = 0; i < dinosaurs.size(); i++) {
                if(dinosaurs.get(i).equals(dino)) {
                    dinosaurs.remove(i);
                }
            }
        }
    } else if(dH < 0) {   //defender has the big defense
        System.out.println("\t" + this + " just lost " + dH + " health!");
        this.addHealth(dH);
        badDinos.add(dino);
    }
}

I have seen some stuff about Iterators, is that what I should use? If so, how do they work? Should I just create a new ArrayList in move()/battle() and timeToReproduce() and then remove stuff after finishing the dinosaurs loop? If so, how do I make sure that dinosaurs that were supposed to be eaten actually are?

I will keep updating with details as people ask for them.