BST graphical representation needed in java

Question

I am using Model–view–controller design pattern, I need a UI Viewer for my BST/AVL models ,I already developed the Model and controller logics, I just need the viewer, I do not need to deal with graphics right now, it would be useful if someone has a Viewer class with a method that takes the root of a tree and draws it, no need for advanced animation or effects

something like

SimpleBSTreeViewer.draw(myTree.getRoot());

node structure of the tree

public class NodeBST <T extends Comparable<T>> {
 private T data;
 private NodeBST<T> left;
 private NodeBST<T> right;
 private NodeBST<T> parent;
 
 //other methods go here ...
}

this would be helpful to focus of coding the logic part,

I have searched and found other java applets that represents trees but they have the model-logic and view in same class , I am working in model-view-controller pattern (MVC pattern) , it is better to separate model from view as much as possible , I just want a viewer for my model

-Note: this is a sample of what i need (I already use JTree and it is not satisfactory.)

enter image description here

JGraph is quite easy to use. http://www.jgraph.com/ Or you can just use JTree. — NeplatnyUdaj, Mar 20 '14 at 14:29
You can build the viewer easily yourself using http://download.java.net/jdk8/jfxdocs/javafx/scene/control/TreeItem.html and http://download.java.net/jdk8/jfxdocs/javafx/scene/control/TreeView.html. — Oliver Jan Krylow, Mar 20 '14 at 15:42
If you are having trouble coding the logic, a debugger would do as good as a display of your tree. — William Morrison, Mar 23 '14 at 08:26

score 4 · Accepted Answer · edited May 23 '17 at 12:20

Get Jgraphx library and starting from HelloWorld in the examples I coded this class

Using this question to calculate coordinates of the nodes.

package algorithms.searching.bst;

import java.util.Random;

import javax.swing.JFrame;

import log.Logger;

import algorithms.searching.bst.avl.AVL;

import com.mxgraph.swing.mxGraphComponent;
import com.mxgraph.view.mxGraph;

@SuppressWarnings("serial")

public class TreeViewer<T extends Comparable<T>> extends JFrame {

static private int CANVAS_HEIGHT = 600;
static private int CANVAS_WIDTH = 1000;

private int rootY = 10;
private int NODE_SIZE = 25;
private int ROW_HEIGHT = 50;
mxGraph graph = new mxGraph();
Object parent = graph.getDefaultParent();

/**
 * draws a tree starting from this root
 * 
 * @param root
 * @param depth
 *            number of nodes to the root (including root)
 * @param index
 *            index of node in this level (leftChildIndex = parentIndex * 2
 *            - 1) and (rightChildIndex = parentIndex * 2)
 * @return
 */
public Object drawTree(NodeBST<T> root, int depth, int index) {
    if (root == null) {
        return null;
    }

    // draw root

    /*
     * leftChildIndex = parentIndex * 2 - 1 
     * rightChildIndex = parentIndex *2
     *
     *
     * x = index * canvasWidth / (2^depth + 1)
     *
     * y = depth * canvasHeight / treeDepth
     */

    int myX = (int) ((CANVAS_WIDTH * (index)) / (Math.pow(2, depth - 1) + 1));

    Object rootVertex = graph.insertVertex(parent, null, root.getData(),
            myX, depth * ROW_HEIGHT + rootY, NODE_SIZE, NODE_SIZE);

    Logger.log("new x coordinate=" + myX);

    // recurse for right child

    Object rightChildVertex = drawTree(root.getRight(), depth + 1,
            index * 2);

    if (rightChildVertex != null) {// edge
        graph.insertEdge(parent, null, "R", rootVertex, rightChildVertex,
                "startArrow=none;endArrow=none;strokeWidth=1;strokeColor=green");
    }

    Object leftChildVertex = drawTree(root.getLeft(), depth + 1,
            index * 2 - 1);

    // recurse for right child

    if (leftChildVertex != null) { // edge
        graph.insertEdge(parent, null, "L", rootVertex, leftChildVertex,
                "startArrow=none;endArrow=none;strokeWidth=1;strokeColor=green");
    }

    return rootVertex;

}

/**
 * Redraw the whole tree
 * 
 * @param root
 *            the root of tree to be drawn
 */

public void update(NodeBST<T> root) {

    graph.getModel().beginUpdate();

    try {

        Object[] cells = graph.getChildCells(parent, true, false);
        graph.removeCells(cells, true);
        drawTree(root, 1, 1);

    } finally {
        graph.getModel().endUpdate();
    }
}

public TreeViewer(NodeBST<T> root) {
    // super("Hello, World!");

    this.update(root);

    mxGraphComponent graphComponent = new mxGraphComponent(graph);

    getContentPane().add(graphComponent);
}

public static void main(String[] args) {

    AVL<Integer> bst = new AVL<Integer>();//use AVL tree class 

    Random randomGenerator = new Random();
    for (int i = 0; i < 20; i++) {//try generating 20 random integers
        bst.insert(randomGenerator.nextInt(1000));
    }

    TreeViewer<Integer> myTreeViewer=new TreeViewer<Integer>(bst.getRoot());
    JFrame frame = myTreeViewer;

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(CANVAS_WIDTH, CANVAS_HEIGHT);
    frame.setVisible(true);

}



}

simply modify this class to take your tree class
Thank you very much NeplatnyUdaj !

Viewing AVL tree

updated version of TreeViewer in my repository [here](https://github.com/Amr1977/Assignments/blob/master/algorithms/searching/bst/TreeViewer.java) — Amr Lotfy, Mar 31 '14 at 16:54

BST graphical representation needed in java

1 Answers1