// Supplementary to "Software Design ...", John A Robinson, Newnes, 2004,
import java.io.*;
class stack
// Not a public class: only used in this file (for this example).
	{
	// First come the private data items
	int stack_length; 		// To allow the caller to set max length
	int stack_base[]; 		// Stack array
	int stack_pointer;
	public stack(int size) 		// This is the constructor
		{
		stack_base = new int[stack_length = size];
		stack_pointer = 0;
		};
	// No destructor necessary
	public int push(int value)
		{
		if (stack_pointer == stack_length)
			return(-1); // Stack full
		stack_base[stack_pointer++] = value;
		return(0);
		}
	public int pop(int value[])
	// Primitive objects can't be passed by reference in Java, so we
	// have to create an array (or an object) in the caller and pass
	// it (because non-primitive objects are always passed by reference).
	// If writing from scratch rather than translating from C++, we
	// might instead maintain a stack of stack_objects rather than of
	// ints.
		{
		if (stack_pointer == 0)
			return(-1); // Stack empty
		value[0] = stack_base[--stack_pointer];
		return(0);
		}
	};
public class stacktest {
    public static void main(String args[])
	{
	stack my_stack = new stack(10); // Note initialization, not
					// stack my_stack(10);
	// Saying that I won't be putting more
	// than 10 items on the stack.
	my_stack.push(345);
	my_stack.push(678);
	// Here is the array we declare so as to pass by reference.
	int test[] = new int[1];
	my_stack.pop(test);
	System.out.println(test[0] + " was just popped off the stack");
	}
    }