Linked List : Adding Recursively
I have a linked list, which can extract data from a random access file. But i need it to be edited so that the actual list will change. But when i try to add something in the middle of the list, everything past the list dissapears. I need to replace one deafult entry with the users entry.
The code:
Linked List Class
class LinkedListNode{
private String day;
privateint abs;
private LinkedListNode next;
public LinkedListNode(){
this(" ", 0);
}
public LinkedListNode(String s1,int s2){
day = s1;
abs = s2;
next =null;
}// LinkedListNode()
publicvoid setData(String s1,int s2){
day = s1;
abs = s2;
}// setData()
public String getDay(){
return day;
}// getday()
public String getData(){
return day +"\t" + abs;
}// getData()
public String toString(){
return day +"\t" + abs;
}// toString()
publicvoid setNext(LinkedListNode nextPtr){
next = nextPtr;
}// setNext()
public LinkedListNode getNext(){
return next;
}// getNext()
}// LinkedListNode class
User entry:
int point = inputInt("Select insertion point: ");
node = head;
addRecursive(point,"just a test");
Method to insert data:
publicvoid addRecursive(int i, String o){
int count = 0;
if(i == 1){
node.setNext(new LinkedListNode(o.trim(),5) );
node.getNext();
}
elseif (node.getNext() !=null){
node = node.getNext();
addRecursive(i-1, o);
}
else output("End of list reached");
}
Thanks in advance
If you're losing all the nodes after the newly inserted one, it sounds like you're not attaching the end of the list to the new node properly.
Say you have a list with 2 nodes, A and C. A's next is pointing to C currently. You insert new node B in between A and C. You set A's next to point to B, then set B's next to point to C. Make sure you're doing the part where you point b's next to C.
public void addRecursive(int i, String o) {
int count = 0; // used for what?
if(i == 1) {
node.setNext(new LinkedListNode(o.trim(),5) ); // no checking whether this node was already present
node.getNext(); // used for what?
}
else if (node.getNext() != null) {
node = node.getNext(); // where's "node" declared?
addRecursive(i-1, o);
}
else output("End of list reached");
}
public void addRecursive(int i, String o) {
int count = 0; // not used for anything, previously used for flagging, redundant now
if(i == 1) {
node.setNext(new LinkedListNode(o.trim(),5) ); // no checking whether this node was already present
// there will always be a node there, it is based on the days of the year, so there will always be a day present, the integer assigned is what i want to change
node.getNext(); // used for what? - not quite sure...
}
else if (node.getNext() != null) {
node = node.getNext(); // where's "node" declared? - outside the method, as a static
addRecursive(i-1, o);
}
else output("End of list reached");
}
public void addRecursive(int i, String o) {
int count = 0; // remove it
if(i == 1) {
node.setNext(new LinkedListNode(o.trim(),5) );
// there will always be a node there, it is based on the days of the year, so there will always be a day present, the integer assigned is what i want to change
// Well, you replace the node that existed as a "next node" before without
// passing its "tail" of other nodes to the newly created one. I'm not sure
// whether you want to replace or insert a node
node.getNext(); // remove it
}
else if (node.getNext() != null) {
node = node.getNext();
// where's "node" declared? - outside the method, as a static
// Static? Then it'll work only for one single linked list in your program; make it non-static
addRecursive(i-1, o); // I guess this should actually be getNext().addRecursive(...), then there's no need for a "node" field at all
}
else output("End of list reached");
}
