In C45PruneableClassifierTree [under J48 decision tree], function public void prune()

Is it possible to calculate the number of prune nodes and leaves on each pruning iteration?

On each pruning iteration, i am able to get the number of nodes and leaves for all of the child.

public static int NumPruneNodes;
for(int k=0; k<m_sons.length; k++){
NumPruneNodes = NumPruneNodes + son(k).numNodes();
}
//m_root.numNodes() does not work here

However, i notice in ClassifierTree.java, it is possible to use m_root.numNodes(), which would result in calculating the current tree number of nodes.

*I am also figuring out whether is it possible to record the number of nodes before a pruning begin, in order for me to generate the difference for number of nodes (before pruning and after pruning).