Considere o seguinte trecho de código em linguagem Java.

                   class S {
                        private int Tamanho;
                        private int[] sArray;
                        private int top;
                   //--------------------------------------------------------------
                        public S(int s) // constructor
                        {
                                 Tamanho = s;
                                 sArray = new long[Tamanho]; // create array
                                 top = -1;
                         }
                   //--------------------------------------------------------------
                         public void coloca(int j)
                         {
                                 sArray[++top] = j;
                        }
                   //--------------------------------------------------------------
                         public long tira()
                         {
                                  return sArray[top--];
                        }
                   //--------------------------------------------------------------
                   } // end class S

Esse trecho implementa uma classe que corresponde a uma