String to Binary Tree and vice versa

[jakko100]

Hello almighty Java gurus,

I have a little task and I have no thoughts at all anymore. I must convert a string ( like A(B,C) or A(B(C,D), E(F)) ) that represents a left-representation of binary tree. I must convert into a object and after that turn it around - I must make a right-representation of a string from object.

I made a class below:

import java.util.*;

public class kodutoo_5 implements Enumeration<kodutoo_5> {
	private String name;
	private kodutoo_5 firstChild;
	private kodutoo_5 nextSibling;
	
	kodutoo_5(String n, kodutoo_5 d, kodutoo_5 r) {
		setName(n);
		setNextSibling(d);
		setFirstChild(r);
	}
	
	kodutoo_5() {
		this("", null, null);
	}
	
	kodutoo_5(String n) {
		this(n, null, null);
	}
	
	public String getName() {
		return name;
	}
	
	public void setName(String name) {
		this.name = name;
	}
	
	public kodutoo_5 getFirstChild() {
		return firstChild;
	}
	
	public void setFirstChild(kodutoo_5 firstChild) {
		this.firstChild = firstChild;
	}
	
	public kodutoo_5 getNextSibling() {
		return nextSibling;
	}
	
	public void setNextSibling(kodutoo_5 nextSibling) {
		this.nextSibling = nextSibling;
	}
	
	public String toString() {
		return getName();
	}
	
	public boolean hasMoreElements() {
		return (getNextSibling() != null);
	}
	
	public kodutoo_5 nextElement() {
		return getNextSibling();
	}
	
	public Enumeration<kodutoo_5> child() {
		return getFirstChild();
	}
	
	private static kodutoo_5 addChild(kodutoo_5 parent, kodutoo_5 current, String nodeString) {
		kodutoo_5 result = current;
		
		//kui alluvaid ei ole, siis jarelikult juurtipp
		if(parent.getFirstChild() == null) {
			//lisame alluva
			parent.setFirstChild(new kodutoo_5(nodeString));
			result = parent.getFirstChild();
		//alluvaid on
		} else {
			result.setNextSibling(new kodutoo_5(nodeString));
			result = result.getNextSibling();
		}
		
		return result;
	}
	
	public static kodutoo_5 parseTree(String s) {
		kodutoo_5 emptyRoot = new kodutoo_5();
		parseTree(emptyRoot, s, 0);
		
		return emptyRoot.getFirstChild();
	}
	
	private static int parseTree(kodutoo_5 parent, String s, int position) {
		kodutoo_5 current = null;
        StringBuilder nodeVal = new StringBuilder();
        
        //alustame string parsimist
        for (int i = position; i < s.length(); i++) {
        	//kui leiame '('
        	if (s.charAt(i) == '(') {
        		if (nodeVal.length() > 0) {
        			current = addChild(parent, current, nodeVal.toString());
        			nodeVal = new StringBuilder();
        		}
        		
        		i = parseTree(current, s, i + 1);
        	//kui leiame ')'
        	} else if (s.charAt(i) == ')') {
        		if (nodeVal.length() > 0) {
        			current = addChild(parent, current, nodeVal.toString());
        			nodeVal = new StringBuilder();
        		}
                        
        		return i;
        	//kui leiame ','
        	} else if (s.charAt(i) == ',') {
        		if (nodeVal.length() > 0) {
        			current = addChild(parent, current, nodeVal.toString());
        			nodeVal = new StringBuilder();
        		}
        	//kui on elemendi sisu
        	} else {
        		nodeVal.append(s.charAt(i));
        	}
        }
        
        if (nodeVal.length() > 0) {
        	current = addChild(parent, current, nodeVal.toString());
        }
        
        return s.length();
	}
	
	public String rightParentheticRepresentation() {
		StringBuilder sb = new StringBuilder();
		
		//kontrollime kas juurtipp eksisteerib
		if (getName() == null) {
			throw new NullPointerException("Puud ei eksisteeri!");
		}
		
		//kontrollime ega juurtipp tuhi ei ole
		if (getName() == "") {
			throw new RuntimeException("Puud ei eksisteeri!");
		}
		
		//juurtipp eksisteerib, jarelikult ka puu
		if (getFirstChild() != null) {
			sb.append("(");
			sb.append(getFirstChild().rightParentheticRepresentation());
			Enumeration<kodutoo_5> child = child();
			
			while (child.hasMoreElements()) {
				sb.append(",");
				child = child.nextElement();
				sb.append(((kodutoo_5) child).rightParentheticRepresentation());
			}
			
			sb.append(")");
		}
		
		sb.append(getName());
		
		return sb.toString();
	}
	   
	public static void main(String[] args) {
		String s1 = "A(B,C)";
		String s2 = "A(B(C,D),E(F))";
		
		kodutoo_5 t1 = kodutoo_5.parseTree(s1);
		kodutoo_5 t2 = kodutoo_5.parseTree(s2);
		
		String v1 = t1.rightParentheticRepresentation();
		String v2 = t2.rightParentheticRepresentation();
		
		System.out.println(s1 + " ==> " + v1);
		System.out.println(s2 + " ==> " + v2);
	}
}

It work's like a charm, but my teacher won't accept this, because he's wants to see that I'm using StringTokenizer class in parseTree method. So I started to rebuild my class and ended up here:

import java.util.*;

public class kodutoo_5 implements Enumeration<kodutoo_5> {
	private String name;
	private kodutoo_5 firstChild;
	private kodutoo_5 nextSibling;
	
	kodutoo_5(String n, kodutoo_5 d, kodutoo_5 r) {
		setName(n);
		setNextSibling(d);
		setFirstChild(r);
	}
	
	kodutoo_5() {
		this("", null, null);
	}
	
	kodutoo_5(String n) {
		this(n, null, null);
	}
	
	public String getName() {
		return name;
	}
	
	public void setName(String name) {
		this.name = name;
	}
	
	public kodutoo_5 getFirstChild() {
		return firstChild;
	}
	
	public void setFirstChild(kodutoo_5 firstChild) {
		this.firstChild = firstChild;
	}
	
	public kodutoo_5 getNextSibling() {
		return nextSibling;
	}
	
	public void setNextSibling(kodutoo_5 nextSibling) {
		this.nextSibling = nextSibling;
	}
	
	public String toString() {
		return getName();
	}
	
	public boolean hasMoreElements() {
		return (getNextSibling() != null);
	}
	
	public kodutoo_5 nextElement() {
		return getNextSibling();
	}
	
	public Enumeration<kodutoo_5> child() {
		return getFirstChild();
	}
	
	private static kodutoo_5 addChild(kodutoo_5 parent, kodutoo_5 current, String nodeString) {
		kodutoo_5 result = current;
		
		//kui alluvaid ei ole, siis jarelikult juurtipp
		if(parent.getFirstChild() == null) {
			//lisame alluva
			parent.setFirstChild(new kodutoo_5(nodeString));
			result = parent.getFirstChild();
		//alluvaid on
		} else {
			result.setNextSibling(new kodutoo_5(nodeString));
			result = result.getNextSibling();
		}
		
		return result;
	}
	
	public static kodutoo_5 parseTree(String s) {
		kodutoo_5 emptyRoot = new kodutoo_5();
		parseTree(emptyRoot, s);
		
		return emptyRoot.getFirstChild();
	}
	
	private static void parseTree(kodutoo_5 parent, String s) {
		
		kodutoo_5 current = null;
		StringTokenizer st = new StringTokenizer(s, "(),", true);
		StringBuilder sb = new StringBuilder();
		
		
		while(st.hasMoreTokens()) {
			String element = st.nextToken();
			if(element.compareTo("(") == 0) {
				if(sb.length() > 0) {
					current = addChild(parent, current, sb.toString());
					sb = new StringBuilder();
				}
			} else if(element.compareTo(")") == 0) {
				if(sb.length() > 0) {
					current = addChild(parent, current, sb.toString());
					sb = new StringBuilder();
				}
			} else if(element.compareTo(",") == 0) {
				if(sb.length() > 0) {
					current = addChild(parent, current, sb.toString());
					sb = new StringBuilder();
				}
			} else {
				sb.append(element);
			}
		}
		
		if(sb.length() > 0) {
			current = addChild(parent, current, sb.toString());
		}
	}
	
	public String rightParentheticRepresentation() {
		StringBuilder sb = new StringBuilder();
		
		//kontrollime kas juurtipp eksisteerib
		if (getName() == null) {
			throw new NullPointerException("Puud ei eksisteeri!");
		}
		
		//kontrollime ega juurtipp tuhi ei ole
		if (getName() == "") {
			throw new RuntimeException("Puud ei eksisteeri!");
		}
		
		//juurtipp eksisteerib, jarelikult ka puu
		if (getFirstChild() != null) {
			sb.append("(");
			sb.append(getFirstChild().rightParentheticRepresentation());
			Enumeration<kodutoo_5> child = child();
			
			while (child.hasMoreElements()) {
				sb.append(",");
				child = child.nextElement();
				sb.append(((kodutoo_5) child).rightParentheticRepresentation());
			}
			
			sb.append(")");
		}
		
		sb.append(getName());
		
		return sb.toString();
	}
	   
	public static void main(String[] args) {
		String s1 = "A(B,C)";
		//String s2 = "A(B(C,D),E(F))";
		
		kodutoo_5 t1 = kodutoo_5.parseTree(s1);
		//kodutoo_5 t2 = kodutoo_5.parseTree(s2);
		
		String v1 = t1.rightParentheticRepresentation();
		//String v2 = t2.rightParentheticRepresentation();
		
		System.out.println(s1 + " ==> " + v1);
		//System.out.println(s2 + " ==> " + v2);
	}
}

But I can't make it right. Can anybody help me out to make this code work, please?