algorithm - Parse indented text tree in Java

Question

I have an indented file that I need to parsed using java, I need some way to place this in a Section class as shown below

    root
     root1
       text1
         text1.1
         text1.2
       text2
         text2.1
         text2.2

     root2
       text1
         text1.1
         text1.2
       text2
         text2.1
         text2.2.2

I have the class for putting the indented stuff it looks like

public class Section 
{

    private List<Section> children;
    private String text;
    private int depth;
    public Section(String t)
    {
       text =t;
    }

    public List<Section> getChildren()
    {
        if (children == null)
      {
            children = new ArrayList<Section>();
       }
        return children;
}

public void setChildren(List<Section> newChildren)
{
    if (newChildren == null) {
        children = newChildren;
    } else {
        if (children == null) {
            children = new ArrayList<Section>();
        }
        for (Section child : newChildren) {
            this.addChild(child);
        }
    }
}

public void addChild(Section child)
{
    if (children == null) {
        children = new ArrayList<Section>();
    }
    if (child != null) {
        children.add(child);
    }
}

public String getText()
{
    return text;
}

public void setText(String newText)
{
    text =newText;
}
public String getDepth()
{
    return depth;
}

 public void setDepth(int newDepth)
 {
    depth = newDepth;
 }
}

I need some way to parse the file and place it in expected result which us a Section object which would look like below

Section= 

Text="Root"
Children
Child1: Text= "root1" 

        Child1: "text1"
            Child1="Text 1.1"
            Child2="Text 1.2"
        Child2: "text2"
            Child1="Text 2.1"
            Child2="Text 2.2"
            Children
Child2: Text= "root2" 
        Child1: "text1"
            Child1="Text 1.1"
            Child2="Text 1.2"
        Child2: "text2"
            Child1="Text 2.1"
            Child2="Text 2.2"


Here is some code that I have started
   int indentCount=0;
   while(String text = reader.readline()
   {
   indentCount=countLeadingSpaces(String word);
   //TODO create the section here
   }


public static int countLeadingSpaces(String word)
{
    int length=word.length();
    int count=0;

   for(int i=0;i<length;i++)
   {
       char first = word.charAt(i); 
        if(Character.isWhitespace(first))
        {
            count++;           
        }
        else
        {
            return count;
        }
   }

 return count;

}

Answer 1

Surprisingly complex problem... but here's a pseudocode

intialize a stack
push first line to stack
while (there are more lines to read) {
 S1 = top of stack // do not pop off yet
 S2 = read a line
 if depth of S1 < depth of S2 {
  add S2 as child of S1
  push S2 into stack
 }
 else {
  while (depth of S1 >= depth of S2 AND there are at least 2 elements in stack) {
   pop stack
   S1 = top of stack // do not pop
  }
  add S2 as child of S1
  push S2 into stack
 }
}
return bottom element of stack

where depth is the # leading whitespaces. You might have to either modify or wrap the Section class to store the depth of the line.