I am trying to learn some oop in java. What I am trying to do is building a binary tree to convert an ekspresion in reverse police notation to infix notation. The problem is that I have three...

data was an Object, I changed it so a String and did Double.parseDouble(data); instead of ((Double)data).doubleValue();
Now it works. Thank you both :)

You are right. It will never return anything but a double.
I wrote some code. The problem now is that I get a NullPointerException which I dont get. Every operator has two children so the none of...

Hi, I am having some troubles with a recursive function.
The function needs to get a string as an input. The string contains both symbols and numbers. What the function does is doing some operation...

I have a binary tree which I would like to get printed out inorder.
Right now I have this recursice loop:

public void inorder()
{
if(leftChild != null )
...

Hi. I am working on a project where I convert postfix notation to infix and evaluateing it. This includes building an evaluations tree (binary tree). I get how to create nodes, but how do I get the...

So I need to do both this:

ArrayList suggestions = new ArrayList();

and this:

public ArrayList<String> suggestions( String word )
{

return suggestions;

Hi. If given an arraylist in an interface like this:

interface Dictionary {
public boolean hasWord(String word);
public ArrayList<String> suggestions( String word );
public void addWord(...

Thank you. That was really helpfull :)

http://www.java2s.com/Tutorial/Java/0180__File/0260__BufferedReader.htm

Hi,
I need to make a big-theta notation on an algoritm I made. The algoritm is soposed to find factors of a number. This is the algoritm implemented in java:

public class factor {

public...