public void deleteAtFront() {
if (header != null && header.getNext() != null) {
header = header.getNext();
// header has null data but some reference point. The get symbol '=' changes the reference
// point. header.getNext() returns the second node in the list
}
}
public void pop() // For stacks, where a node at the end of the list is deleted
{
if (header.getNext() == null) // if there is not second node AKA one node in the list
{
header = null; // header points to nothing
} else if (header.getNext()
!= null) // If there is a second node AKA more than two nodes in the list
{
header = header.getNext(); // header points to the second node in the list.
}
}
public int sumOfStock(IngredientNode n) {
if (n == null) {
return 0;
} else {
return n.getIngredient().getStock() + sumOfStock(n.getNext());
}
}
public void push(
Ingredient a) // For stacks, where a node of data a is inserted at the end of the list
{
if (header == null) {
header = new IngredientNode(a, null); // header points to the new node
} else {
IngredientNode current = header;
while (current.getNext() != null) // second node doesn't equal to null
{
current =
current
.getNext(); // second node gets third node...third node gets fourth node...until the
// LAST NODE (current.getNext() == null)
}
current.setNext(new IngredientNode(a, null)); // Set reference for last node to the new node
}
}
public String printData() {
IngredientNode current = header;
String s = "";
while (current != null) {
s = s + "\n" + current.getIngredient();
current = current.getNext();
}
return s;
}
public void delete(Ingredient n) {
IngredientNode current = header;
IngredientNode previous = null;
while (current != null) {
if (current.ingredient.equals(n)) {
if (previous == null) // This means that the first node is the target node
{
header = header.getNext();
previous = current;
} else {
previous.setNext(current.getNext());
current = null;
}
} else {
previous = current;
current = current.next;
}
}
}