Pool.java

package aurelienribon.tweenengine;

import java.util.ArrayList;

/**
 * A light pool of objects that can be resused to avoid allocation.
 * Based on Nathan Sweet pool implementation
 */
abstract class Pool<T> {
	private final ArrayList<T> objects;
	private final Callback<T> callback;

	protected abstract T create();

	public Pool(int initCapacity, Callback<T> callback) {
		this.objects = new ArrayList<T>(initCapacity);
		this.callback = callback;
	}

	public T get() {
		T obj = objects.isEmpty() ? create() : objects.remove(objects.size()-1);
		if (callback != null) callback.onUnPool(obj);
		return obj;
	}

	public void free(T obj) {
		if (!objects.contains(obj)) {
			if (callback != null) callback.onPool(obj);
			objects.add(obj);
		}
	}

	public void clear() {
		objects.clear();
	}

	public int size() {
		return objects.size();
	}

	public void ensureCapacity(int minCapacity) {
		objects.ensureCapacity(minCapacity);
	}

	public interface Callback<T> {
		public void onPool(T obj);
		public void onUnPool(T obj);
	}
}