Recursive function - to get Children(might be parents too) of parents - URGENT PLEAS

[peter brews]

Hi
Can anyone of you help me with the source code for this recursion problem, I will truely appreciate this has been haunting me for some days now.
The problem is, I have 2 fields
Node_id ParentNode
B A
C A
D B
E B
F B
G C
H E
I E
And the list could go on indefinitely. What I want is the output which accepts a Parent_nod (Example A) and lists all the children
{B,C,D,E,F,G,H,I) preferable output will be (B,D,E,H,I,F,C,G List a parent and the childs of that parents)
I know I can solve this with a recursive function but an stuck now
Please help

[Ernest Friedman-Hill]

What have you tried so far? Show us what you've got.

[Julie de Wet]

My two cents worth
Well obviously the terminating condition is when the node is a leaf and doesn't have any children.
ArrayList (??) nodes; // just as an example
printChildren(Node parent)
{
for(int i = 0; i != nodes.size(); i++)
{
Node node = (Node)nodes.get(i);
if(node.parent_id.equals(parent.node_id))
{
System.out.println(node.node_id);
printChildren(node);
}
}
}

[Stan James]

I'd expect to see something like this:

in node class
{
   String interestingText
   Set children
}
  
in someOtherClass
{ 
   printNodeAndChildren(node)
   {
      print node.interesting text
      for each child
         printNodeAndChildren(child)
      next
   }
}

This terminates when there are no children. If you're loading your tree of nodes from a text file as shown, make sure you don't say A->B and B->A or it will run forever!
To make it print as an outline, with cool indentation, keep track of recursion depth. Pass a level of 0 when first calling printNodeAndChildren, then pass level+1 when calling itself recursively. Print that many spaces in front of the value.

A
  B
    D
    E
      H
      I
    F
  C
    G