Add listener to ArrayList

user_597657 0
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I have an ArrayList which I add some Objects to it dynamically, and I have a JButton. The ArrayList is empty when running my program and the JButton is set to setEnabled(false). I want to enable my button whenever there are 2 elements in the ArrayList or more and disable it again if the ArrayList has one item or empty. How can I achieve this?

listener arraylist java
8 Answers

If you need to fix this issue using only java.util.ArrayList you can use below solution. I don't know this is the exact solution you want. But you can achieve your need as below.

Implement what should happen after added and removed. Customize this interface as you needed. 

public interface ListBehaviorHandler {

    void afterAdded();
    void afterDeleted();
}

And use below method to get custom behave list. 

public <E> List<E> getCustomList(ListBehaviorHandler listBehaviorHandler) {
    return new ArrayList<E>() {
        @Override
        public boolean add(E e) {
            boolean added = super.add(e);
            listBehaviorHandler.afterAdded();
            return added;
        }

        @Override
        public void add(int index, E element) {
            super.add(index, element);
            listBehaviorHandler.afterAdded();
        }

        @Override
        public E remove(int index) {
            E removed = super.remove(index);
            listBehaviorHandler.afterDeleted();
            return removed;
        }

        @Override
        public boolean remove(Object o) {
            boolean removed = super.remove(o);
            listBehaviorHandler.afterDeleted();
            return removed;
        }
    };
}
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