public class LLStack { private java.util.LinkedList list = new java.util.LinkedList(); public LLStack() { } public void clear() { list.clear(); } public boolean isEmpty() { return list.isEmpty(); } public Object topEl() { if (isEmpty()) throw new java.util.EmptyStackException(); return list.getLast(); } public Object pop() { if (isEmpty()) throw new java.util.EmptyStackException(); return list.removeLast(); } public void push(Object el) { list.add(el); } public String toString() { return list.toString(); } }