How to visually print a NON binary tree?

Question

I made a basic tree where all the nodes have a name and a set of children.

public class Tree {
    String data;
    Tree parent = null;
    HashSet children = new HashSet();

    public Tree(String nodeName) {
        this.data = nodeName;
    }

    public void parent(Tree parent) {
        this.parent = parent
    }

    public void addAChild(Tree child) {
        this.children.add(child);
        child.parent(this);
    }

And to use this class

Tree a = new Tree("root");
Tree b = new Tree("n1");
Tree c = new Tree("n2");
Tree d = new Tree("n3");
Tree e = new Tree("n4");
Tree f = new Tree("n5");

a.addAChild(b);
a.addAChild(c);
a.addAChild(d);

d.addAChild(e);
e.addAChild(f);

This makes sense to me but I'd like a visual representation of the tree so that I can quickly test to see if the children and nodes are in the right place.

I'm trying to make the output look like this:

Or something similar.

Answer 1

A quick and dirty way of printing the tree would involve adding a method like this to your Tree class:

public void print(int level) {
    for (int i = 1; i < level; i++) {
        System.out.print("\t");
    }
    System.out.println(data);
    for (Tree child : children) {
        child.print(level + 1);
    }
}

level represents the level of the node in the tree, which is defined as 1 + (the number of connections between the node and the root). It dictates how much the node will be indented in the output.

Then you can print the tree by printing the root (the level of the root is 1):

a.print(1);

Getting output like this:

root
    n1
    n2
    n3
        n4
            n5