import java.util.LinkedList;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.collections.ModifiableObservableListBase;
import javafx.collections.ListChangeListener;
import java.util.Collection;
import java.util.Arrays;
 
public class Main {
	public static void main(String[] args) {
		ObservableList<String> test = new ObservableLimitedList<>(5);
 
		test.addListener((ListChangeListener<String>)(change -> {
			System.out.println("change: " + change);
		}));
 
		test.add("test1");
		test.add("test2");
		test.add("test3");
		test.add("test4");
		test.add("test5");
		test.add("test6");
		test.add("test7");
 
		System.out.println("final list: " + test);
	}
}
 
class ObservableLimitedList<T> extends ModifiableObservableListBase<T> {
	private LinkedList<T> list;
	private int maxSize;
 
	public ObservableLimitedList(int maxSize) {
		this.maxSize = maxSize;
		list = new LinkedList<>();
	}
 
	@Override
	public boolean add(T element) {
		boolean result = super.add(element);
		if (size() > maxSize) {
			remove(0);
		}
		return result;
	}
 
	// delegate overrides:
 
	@Override
	public T get(int index) {
		return list.get(index);
	}
 
	@Override
	public int size() {
		return list.size();
	}
 
	@Override
	protected void doAdd(int index, T element) {
		list.add(index, element);
	}
 
	@Override
	protected T doSet(int index, T element) {
		return list.set(index, element);
	}
 
	@Override
	protected T doRemove(int index) {
		return list.remove(index);
	}
}

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