使用ID java插入列表

Question

Currently I have a method to insert behaviors into a List from another class called Aptitude . Behaviors have an ID and I want to insert the next behavior created into the list with the next available ID not present in the whole List. I'm doing it like this:

public Behavior addBehavior(BehaviorDto behaviorDto, String aptitudeId) {
    Aptitude aptitude;
    aptitude = findById(aptitudeId);
    List<Behavior> behaviors = aptitude.getBehaviors();
    int nextId = -1;
    boolean flag;
    for (int i = 1; i <= behaviors.size() + 1; i++) {
        flag = true;
        for (Behavior behavior1 : behaviors) {
            if (Integer.parseInt(behavior1.getId()) == i) {
                flag = false;
                continue;
            }

        }
        if (flag) {
            nextId = i;
            break;
        }
    }

But I remember being told that there was a way to optimize and not need to use a flag variable.

How can I improve this code?

edit

the rest of the method:

Behavior behavior = new Behavior(String.valueOf(nextId), behaviorDto.getEn(), behaviorDto.getEs());
behavior.setId(String.valueOf(nextId));
aptitude.addBehavior(behavior);
updateAptitude(aptitude);
return behavior;

Answer 1

I would expect Aptitude to 'know' the next available behavior id (Object Oriented) .

public Behavior addBehavior(BehaviorDto behaviorDto, String aptitudeId) {
    Aptitude aptitude = findById(aptitudeId);
    List<Behavior> behaviors = aptitude.getBehaviors();
    int nextId = aptitude.getNextBehaviorId()

    // ...
}

Answer 2

You can move id generation to Behavior's constructor:

class Behavior {
    private static AtomicInteger counter = new AtomicInteger(0);

    public Behavior(BehaviorDto behaviorDto) {
        \\other constructor things
        this.id = counter.incrementAndGet();
    }
}

After this be done, you can just do:

public Behavior addBehavior(BehaviorDto behaviorDto, String aptitudeId) {
    Aptitude aptitude;
    aptitude = findById(aptitudeId);
    List<Behavior> behaviors = aptitude.getBehaviors();
    Behavior newBehavior = new Behavior(behaviorDto);
    behaviors.add(newBehavior);
    return newBehavior;
}