A Level-2-Tree app with AddObject NLSTree

by Raul Aguilar

download here

Here is a niffty algorithm to display create a child-parent tree structure for the AddObject NLSTree tool. I'm not paid by the AddObject folks but did find the NLSTree tool sufficiently awesome enough write-up a use application.

It takes an input of level-node entries and produces an output of tree.add(..) statements. Well, as an example consider this tree of colors for in.txt where white is a child and yellow a grandchild of blue.

in.txt

1	blue
2	white
2	red
3	yellow
4	orange
3	violet
2	cyan
3	green
4	black
5	brown

Each Java application needs method static main(..) so here is the Level2TreeX.java class instancing Level2Tree.java dynamic class

Level2TreeX.java

public class Level2TreeX {

  public static void main(String[] argc) {

    Level2Tree l2t = new Level2Tree();
    l2t.process(argc[0]);
  }
}

Each row in the file is tab delimited and parsed with the Java String split("\t") in method fileGetLine(). You'll notice method stringFilter(..) handles the task of a regular expression but in atomic i-just-gotta-code-it-myself sytle. Really for the life of me i had no idea how to filter and replace undesired characters but if it works. Actually, this is the first time i used the StringBuffer() class for this purpose so it was quite an encouraging path (for an old-time newbie like myself). Method algorithm() is the star of the show with a hack-up logic contruct - it works, yeah it's my fault but don't know how it got coded!.

Level2Tree.java

import java.util.ArrayList;
import java.io.BufferedReader;
import java.io.FileReader;

public class Level2Tree {

  public void process(String filename) {

    fileStart(filename);
    ArrayList out = algorithm();
    fileEnd();

    for (int i=0; i < out.size(); ++i) {
      System.out.println(out.get(i));
    }

  }

  public ArrayList algorithm() {

    //	 control vars
    ArrayList parent = new ArrayList();
    ArrayList tree = new ArrayList();

    String[] fields;
    while (null != (fields = fileGetLine())) {

      String rowLevel = fields[0];
      String rowNode = stringFilter(fields[1]);

      int level = Integer.parseInt(rowLevel, 10);

      if (parent.size() == level) {
        // has same parent

      } else if (parent.size() < level) {
        // is new parent
        // assume levels always increase by one
        parent.add(rowNode);

      } else {
        // regress to earlier parent
        while (level <= parent.size()) {
          // remove last
          parent.remove(parent.size()-1);
        }
        parent.add(rowNode);
      }

      int pos = parent.size()-2;
      String parentID;
      if (pos < 0) {
        parentID = "null";
      } else {
        parentID = (String) parent.get(pos);
      }
      String line =
        "tree.add(\"" +
          rowNode + "\",\"" +
          parentID + "\",\"" +
          rowNode + "\",\"\",\"\",0,0,\"\",\"" +
          rowNode + "\");";
      tree.add(line);
    }
    return tree;
  }

  public String stringFilter(String str) {

    String out;
    if (null == str) {
      out = "";
    } else {

      str = str.trim();
      StringBuffer sb = new StringBuffer();
      for (int i=0; i < str.length(); ++i) {
        char c = str.charAt(i);
        String toSuffix = String.valueOf(c);
        if (false) {

        // rid of double quote
        } else if (c == '"') {
          toSuffix = "";

        // replace ampersand
        } else if (c == '&') {
          toSuffix = "&";

        }
        sb.append(toSuffix);
      }
      out = sb.toString();
    }
    return out;
  }

  BufferedReader br;

  void fileStart(String filename) {

    try {

      //  set up a file reader to read each expression line.
      FileReader fr = new FileReader(filename);
      br = new BufferedReader(fr);

    } catch (Exception e) {
      System.out.println("error, msg: " + e.getMessage());
      System.exit(0);
    }
  }

  String[] fileGetLine() {

    String[] out;
    String line;

    out = null;
    try {

      // read new code line.
      if ((line = br.readLine()) != null) {
        line = line.trim();
        out = line.split("\t");
      }

    } catch (Exception e) {
      System.out.println("error, msg: " + e.getMessage());
      System.exit(0);
    }

    return out;
  }

  void fileEnd() {

    try {
      br.close();
    } catch (Exception e) {
      System.out.println("error, msg: " + e.getMessage());
      System.exit(0);

    }
  }
}

In any case, the output result here is neatly consumed by the AddObject Object NLSTree tool.

out.txt

tree.add("blue","null","blue","","",0,0,"","blue");
tree.add("white","blue","white","","",0,0,"","white");
tree.add("red","blue","red","","",0,0,"","red");
tree.add("yellow","white","yellow","","",0,0,"","yellow");
tree.add("orange","yellow","orange","","",0,0,"","orange");
tree.add("violet","white","violet","","",0,0,"","violet");
tree.add("cyan","blue","cyan","","",0,0,"","cyan");
tree.add("green","cyan","green","","",0,0,"","green");
tree.add("black","green","black","","",0,0,"","black");
tree.add("brown","black","brown","","",0,0,"","brown");

On the next article, i'll show you how to wrap-up this core functionality into a displayable tree.