In my main method, when I create an empty SLList, and I call the addLast_iterative() method, if I try to create a reference to the null instance variable 'first' (within addLast_iterative()), then try to reference a new node with the corresponding value, it doesn't change the previous reference 'first' to reference the new IntNode object? I have gotten it to work, but am curious why this doesn't change 'first' to reference to newly created IntNode object. You can skip ahead to addLast_iterative(int x) if this is unclear. I commented out the part that doesn't work, the top "if" loop does work. In other words, "first" still will reference Null, if I use the 'if' statement I commented out. Thanks
public class SLList {
private static class IntNode {
public int item;
public IntNode next;
public IntNode(int i, IntNode n) {
this.item = i;
this.next = n;
}
}
private IntNode first;
private int size;
/* initialize empty SLList */
public SLList() {
this.first = null;
this.size = 0;
}
public SLList(int x) {
this.first = new IntNode(x, null);
this.size = 1;
}
public void addFirst(int x) {
this.first = new IntNode(x, this.first);
size += 1;
}
public int getFirst() {
return this.first.item;
}
/*************************************************************/
public void addLast_iterative(int x) {
this.size += 1;
if (this.first == null) {
this.first = new IntNode(x, null);
return;
}
IntNode p = this.first;
// why does this bottom 'if' statement not work, but the top
//does?
/*if (p == null) {
p = new IntNode(x, null);
return;
}*/
while(p.next != null) {
p = p.next;
}
p.next = new IntNode(x, null);
}
/*************************************************************/
/*************************************************************/
public int size() {
return size;
}
/*************************************************************/
public static void main(String[] args) {
SLList lst = new SLList();
lst.addLast_iterative(3);
}
}
