java - How to Traverse a N-Ary Tree -

my tree/node class:

import java.util.arraylist; import java.util.list;  public class node<t> {    private t data;    private list<node<t>> children;    private node<t> parent;     public node(t data) {       this.data = data;       this.children = new arraylist<node<t>>();    }     public node(node<t> node) {       this.data = (t) node.getdata();       children = new arraylist<node<t>>();    }     public void addchild(node<t> child) {       child.setparent(this);       children.add(child);    }     public t getdata() {       return this.data;    }     public void setdata(t data) {       this.data = data;    }     public node<t> getparent() {       return this.parent;    }     public void setparent(node<t> parent) {       this.parent = parent;    }     public list<node<t>> getchildren() {       return this.children;    } } 

i know how traverse binary tree, traversing n-ary seems more tricky.

how go traversing through tree. want counter whilst traverse tree number/count each node in tree.

then @ specific count, can stop , return node @ count (perhaps remove subtree or add subtree @ position).

the simplest way implement visitor pattern this:

public interface visitor<t> {     // returns true if visiting should cancelled @ point     boolean accept(node<t> node); }  public class node<t> {     ...     // returns true if visiting cancelled    public boolean visit(visitor<t> visitor) {        if(visitor.accept(this))            return true;        for(node<t> child : children) {            if(child.visit(visitor))                return true;        }        return false;    } } 

now can use this:

treeroot.visit(new visitor<type>() {     public boolean accept(node<type> node) {         system.out.println("visiting node "+node);         return false;     } }); 

or particular task:

class countvisitor<t> implements visitor<t> {     int limit;     node<t> node;      public countvisitor(int limit) {         this.limit = limit;     }      public boolean accept(node<t> node) {         if(--limit == 0) {             this.node = node;             return true;         }         return false;     }      public node<t> getnode() {         return node;     } }  countvisitor<t> visitor = new countvisitor<>(10); if(treeroot.visit(visitor)) {     system.out.println("node#10 "+visitor.getnode()); } else {     system.out.println("tree has less 10 nodes"); }