converting a list to double

[dav3]

Hi again folks. I have a function called "linearRegressi on()" now I am along way from finishing this function atm. A little about this function: The function executes an SQL query grabbing a column from a table in my database called "Yahoo". Now here is where things are getting fuzzy for me. I need to be able to perform mathematical operations on this result set ie. finding the rsquared value, slope, average etc..... but i cannot do any of this on the list at is is now. I have tried created the list as a "type specific" list, but for whatever reason eclipse is giving me errors. I have tried converting my list to doubles numerous times without any results. Any guidance is appreciated.

 public void linearRegression()
       {
           try 
           {
              List list = new ArrayList();
              result= db_statement.executeQuery("select Close from Yahoo");
              System.out.println ("Query Successful");
 
              while (result.next())
              {
                  list.add(result.getString("close"));
              }
                   System.out.println(list);
           } catch (Exception excep) {
              System.out.println ("Unable to execute query: n" + excep);
              System.exit(0);
           }
       }
 
 

I have omitted all my failed methods of conversion as they were just confusing me further. I figured here would be a good place to ask for guidance. Thanks in advance.

Also is there any reason why creating a list of specific type would not work in Eclipse? i am using Eclipse 3.2 and my java is 1.6.02 (or whatever the most up todate version is)

[dmjpro]

Hi again folks. I have a function called "linearRegressi on()" now I am along way from finishing this function atm. A little about this function: The function executes an SQL query grabbing a column from a table in my database called "Yahoo". Now here is where things are getting fuzzy for me. I need to be able to perform mathematical operations on this result set ie. finding the rsquared value, slope, average etc..... but i cannot do any of this on the list at is is now. I have tried created the list as a "type specific" list, but for whatever reason eclipse is giving me errors. I have tried converting my list to doubles numerous times without any results. Any guidance is appreciated.

 public void linearRegression()
       {
           try 
           {
              List list = new ArrayList();
              result= db_statement.executeQuery("select Close from Yahoo");
              System.out.println ("Query Successful");
 
              while (result.next())
              {
                  list.add(result.getString("close"));
              }
                   System.out.println(list);
           } catch (Exception excep) {
              System.out.println ("Unable to execute query: n" + excep);
              System.exit(0);
           }
       }
 
 

I have omitted all my failed methods of conversion as they were just confusing me further. I figured here would be a good place to ask for guidance. Thanks in advance.

Also is there any reason why creating a list of specific type would not work in Eclipse? i am using Eclipse 3.2 and my java is 1.6.02 (or whatever the most up todate version is)

Is this giving any error in Eclipse?
And the Q. is not clear to me, what O/P you expect..please tell me in details :-)

Kind regards,
Dmjpro.

[dav3]

Sorry m8. No that current function gives me no errors. But I cannot perform math operations on it. for example:

double sum = list(0) + list(1);

will not work because the list elements are objects. I need a way to convert them to doubles... this is probably much easier then I am making it. But thus far repeated attempts have done nothing but "fog" up my code.

[dmjpro]

Sorry m8. No that current function gives me no errors. But I cannot perform math operations on it. for example:

double sum = list(0) + list(1);

will not work because the list elements are objects. I need a way to convert them to doubles... this is probably much easier then I am making it. But thus far repeated attempts have done nothing but "fog" up my code.

Don't use code words, it's a forum not a chatting room :-)
And be specific about your problem.
Are you sure that what you store in list that can be parsed as double?
Then have a look at this code.

double sum = parseDouble(list.get(0)) + parseDouble(list(list.get(1));
 

Kind regards,
Dmjpro.

[dav3]

Thank you for your code, but it did not work "The method parseDouble(Obj ect) is undefined for the type JDBC". So I guess my list cannot be converted into a double?

I have tried

List<Integer> intlist = new ArrayList<Integer>();

but Eclipse gives me errors when I try to use the "<Integer>" or "<double>". So perhaps there is an alternative way to read my result set into something I can work with?

[dmjpro]

Thank you for your code, but it did not work "The method parseDouble(Obj ect) is undefined for the type JDBC". So I guess my list cannot be converted into a double?

I have tried

List<Integer> intlist = new ArrayList<Integer>();

but Eclipse gives me errors when I try to use the "<Integer>" or "<double>". So perhaps there is an alternative way to read my result set into something I can work with?

Sorry I made a mistake.
I am so sorry :-(
It will be Double.parseDou ble(String)
So I am rewriting the code.

double sum = Double.parseDouble((String)list.get(0)) + Double.parseDouble((String)list(list.get(1));
 

Again I am so sorry :-(

Kind regards,
Dmjpro.

[dav3]

Success!!!

Thank you sir. Now i just need to figure out away to sum up all the records, but you have given me the ability to move forward.

Thanks again.

[dmjpro]

Success!!!

Thank you sir. Now i just need to figure out away to sum up all the records, but you have given me the ability to move forward.

Thanks again.

You are welcome buddy :-)
Come again whenever you have problem.
Please check your PM.

Kind regards,
Dmjpro.

[r035198x]

If the values are type decimal in the database, then use

 List<Double> list = new ArrayList<Double>(); 

to declare the arraylist.

Then use rs.getDouble() to retrieve them.

[dav3]

If the values are type decimal in the database, then use

 List<Double> list = new ArrayList<Double>(); 

to declare the arraylist.

Then use rs.getDouble() to retrieve them.

Thank you r035198x (got it right this time:) ). I tried that way but for some odd reason Eclipse was giving me an error. I am using the next to newest version of Eclipse so perhaps that was the issue? Parsing the strings to doubles worked for the time being. My function is going to get far more complex so I might have to look at really finding the source of the error while using the method you suggested. But for now I shall plow ahead.
Thank you again for your advice.