Structuring Data with Java - Java - page 280

protected protected int int depth = 0 ;

/* The actual stack */
protected protected int int [] stack = new new int int [ MAX_DEPTH ];

@Override
public public boolean boolean empty () {

return

return depth == 0 ;

}

@Override
public

public void void push ( Integer n ) {

stack [ depth ++] = n ;

}

@Override
public

public Integer pop () {
return return stack [-- depth ];

}

@Override
public

public Integer peek () {
return

return stack [ depth - 1 ];

}

}

While working on ToyStack2 , I extracted its interface into SimpleStack , which just lists the
operations. At the same time I added the empty() method for some compatibility with the
“standard” java.util.Stack API:

public public interface interface SimpleStack SimpleStack < T > {

/** empty - return true if the stack is empty */
abstract abstract boolean boolean empty ();

/** push - add an element onto the stack */
abstract abstract void void push ( T n );

/** pop - return and remove the top element */
abstract abstract T pop ();

/** peek - return the top element but don't remove it */
abstract abstract T peek ();

}