Data Structures and Algorithm Analysis - Computer Science at ...

Sec. 4.2 Stacks 119/** Array-based stack implementation */class AStack implements Stack {private static final int defaultSize = 10;private int maxSize;private int top;private E [] listArray;// Maximum size of stack// Index for top Object// Array holding stack/** Constructors */AStack() { this(defaultSize); }@SuppressWarnings("unchecked") // Generic array allocationAStack(int size) {maxSize = size;top = 0;listArray = (E[])new Object[size]; // Create listArray}/** Reinitialize stack */public void clear() { top = 0; }/** Push "it" onto stack */public void push(E it) {assert top != maxSize : "Stack is full";listArray[top++] = it;}/** Remove and top element */public E pop() {assert top != 0 : "Stack is empty";return listArray[--top];}/** @return Top element */public E topValue() {assert top != 0 : "Stack is empty";return listArray[top-1];}/** @return Stack size */public int length() { return top; }Figure 4.19 Array-based stack class implementation.