Java method: Finding object in array list given a known attribute value

Question

I have a couple of questions actually.

I have a class Dog with the following instance fields:

private int id;
private int id_mother;         


        

Answer 1

You have to loop through the entire array, there's no changing that. You can however, do it a little easier

for (Dog dog : list) {
  if (dog.getId() == id) {
    return dog; //gotcha!
  }
}
return null; // dog not found.

or without the new for loop

for (int i = 0; i < list.size(); i++) {
  if (list.get(i).getId() == id) {
    return list.get(i);
  }
}