/** * Book: Data Structures and Algorithms in Java, by Robert LaFore * Chapter 4: * stack.java * demonstrates stacks * to compile this code: javac stack.java * to run this program: java StackApp */ class StackX { private int maxSize; // size of stack array private long[] stackArray; private int top; // top of stack public StackX(int s) { // constructor maxSize = s; // set array size stackArray = new long[maxSize]; // create array top = -1; // no items yet } public void push(long j) { // put item on top of stack stackArray[++top] = j; // increment top, insert item } public long pop() { // take item from top of stack return stackArray[top--]; // access item, decrement top } public long peek() { // peek at top of stack return stackArray[top]; } public boolean isEmpty() { // true if stack is empty return (top == -1); } public boolean isFull() { // true if stack is full return (top == maxSize-1); } } // end class StackX class StackApp { public static void main(String[] args) { StackX theStack = new StackX(10); // make new stack theStack.push(20); // push items onto stack theStack.push(40); theStack.push(60); theStack.push(80); theStack.push(100); while (!theStack.isEmpty()) { // until it's empty, long value = theStack.pop(); // delete item from stack System.out.print(value); // display it System.out.print(" "); } System.out.println(""); } }