Unnecessary copy of elements

The method 'resizeStack' from classes 'FastStack' and 'ClassStack' call 'System.arrayCopy' using a length which sometimes is unnecessarily too big.

I suggest you change this method:

private void resizeStack(int newCapacity) { Object[] newStack = new Object[newCapacity]; System.arraycopy(stack, 0, newStack, 0, Math.min(stack.length, newCapacity)); stack = newStack; }

to read as follows:

private void resizeStack(int newCapacity) { Object[] newStack = new Object[newCapacity]; System.arraycopy(stack, 0, newStack, 0, Math.min(pointer, newCapacity)); stack = newStack; }

Since pointer <= stack.length and the elements that come after stack[pointer - 1] will never be read anyway.