Question

I’m new to java and can’t seem to wrap my head around a problem. I’m trying to take two arrays of stock information, and compare them against each other(only keeping the ones that appear in both arrays). I read a bit about generic algorithms and if a match, I wanted to be able to create classes to assign fitness scores to each array set. My code doesn’t really work(I can get it to analyze each individual components of the array but not the range I want it to). To clear things up, here’s a sample of my data:

ID   date   Ticker  Shares
    1   2011-06-19  goog    0
    1   2011-06-19  ibm 0
    1   2011-06-19  gs  0
    1   2011-06-19  msft    0
    1   2011-06-19  c   5
    2   2011-06-19  goog    0
    2   2011-06-19  ibm 0
    2   2011-06-19  gs  0
    2   2011-06-19  msft    1
    2   2011-06-19  c   4
    3   2011-06-19  goog    0
    3   2011-06-19  ibm 0
    3   2011-06-19  gs  0
    3   2011-06-19  msft    2
    3   2011-06-19  c   3
    4   2011-06-19  goog    0
    4   2011-06-19  ibm 0
    4   2011-06-19  gs  0
    4   2011-06-19  msft    3
    4   2011-06-19  c   2
    5   2011-06-19  goog    0
    5   2011-06-19  ibm 0
    5   2011-06-19  gs  0
    5   2011-06-19  msft    4
    5   2011-06-19  c   1 

As so on, I have a array of this and another one for the previous date. I want to be able to compare(grouped by the id’s) the two against each other, and find entire matches. But later on, I want to be able to take the successful matches and perform analytic on them via other classes. I think the first step is identifying a match. Here’s my code(it only identifies a match of ticker/shares, and I’m not sure how to get it to match an entire ID set):

public void compare(int firstindex, int lastIndex, Object date1, ArrayList data1id, ArrayList data1ticker, ArrayList data1shares, ArrayList data1price, Object date2,  ArrayList data2id, ArrayList data2ticker, ArrayList data2shares, ArrayList data2price) throws Exception {
    ArrayList ticker = new ArrayList(); 
    ArrayList shares = new ArrayList(); 
    ArrayList price = new ArrayList(); 

    while (firstindex < lastIndex) {
        //System.out.print("date is " + date1);
        ticker.add(data1ticker.get(firstindex));
        shares.add(data1shares.get(firstindex));
        price.add(data1price.get(firstindex));
        firstindex++;
    }
    comparewithsecondarray(ticker, shares, price, date2, data2id, data2ticker, data2shares, data2price);
    //System.out.println("***********");
}

public void comparewithsecondarray(ArrayList tickerarray, ArrayList sharesarray, ArrayList pricearray, Object date2,  ArrayList data2id, ArrayList data2ticker, ArrayList data2shares, ArrayList data2price) throws Exception {
//get the total number of values in the array
int totalArrayList = tickerarray.size();
int counter= 0;

        System.out.println("Array has been checked against second array and we're on " + counter);
        System.out.println(tickerarray);
        System.out.println(sharesarray);
        System.out.println("+++++++");

    while (counter < totalArrayList) {

        Object ticker = tickerarray.get(counter);
        Object shares = sharesarray.get(counter);
        Object price = pricearray.get(counter);


        loadSecondArray(ticker, shares, price, date2, data2id, data2ticker, data2shares, data2price);
        counter++;
    }

}

public void loadSecondArray(Object ticker, Object shares, Object price, Object date2,  ArrayList data2id, ArrayList data2ticker, ArrayList data2shares, ArrayList data2price) throws Exception {
    //System.out.println("ticker " + ticker);
    //System.out.println("shares " + shares);
    //System.out.println("price " + price);

    //find the last number of the arrray
    if (!data2id.isEmpty()) {
        int counter2 = Integer.parseInt(data2id.get(data2id.size()-1).toString());
        //System.out.println("last element in array2 is " + counter2);
    }        

    //location is the id number we're looking for.
    int location = 1;
    while (location > counter2) {
        boolean blnFound = data2id.contains(location);
        //System.out.println("Does arrayList contain " + location + "? " + blnFound);
        if (blnFound) {

            if(firstindex == -1) {
                //System.out.println("ArrayList does not contain " + location);
            } else {
                //System.out.println("ArrayList contains " + location  + " at index :" + firstindex);
                int firstindex = data2id.indexOf(location);
                int lastIndex = data2id.lastIndexOf(location);
                //send ranges to study

                while (firstindex < lastIndex) {
                    //System.out.print("date is " + date1);
                    Object ticker2 = data2ticker.get(firstindex);
                    Object shares2= data2shares.get(firstindex);
                    Object price2 = data2price.get(firstindex);
                    if (ticker.equals(ticker2) &&  shares.equals(shares2)) {
                        System.out.println("We have a match!");
                        System.out.println(ticker);
                        System.out.println(ticker2);
                        System.out.println(shares);
                        System.out.println(shares2);
                        System.out.println("*****");
                    }
                    //add to the counter
                    firstindex++;
                }

                location++;
            }



        } else {
            break;
        }

    }

Sorry in advance for the quality of the code, I’m pretty new and still learning. I think the first step is to identify the matches, then have a way to pass those matches(as arraylists, I guess) to other classes to analyze.

Any suggestions on how to achieve my goals of this project would be great(I am reading a book on genetic algo’s but its a bit hard to grasp so I’m starting to review all the code I can find on the interne to understand how its being done).

Thanks in advance

Answer 1

I think you may need something like this:

import java.util.Calendar;

//class representing all your data
public class StockData implements Comparable<StockData>{
    private int id;
    private Calendar date;
    private List<ShareBean> shares;

//this will return whichever StockData that has more total shares as being greater
@Override
public int compareTo(StockData arg0) {
    int totalshares = 0;
    int totalshares2 = 0;
    for(ShareBean share: shares)
        totalshares+=share.getShares();
    for(ShareBean share: arg0.getShares())
        totalshares2+=share.getShares();
    return totalshares-totalshares2;
}
    //this method is used to see if another StockData object has the same id
    @Override
    public boolean equals(Object arg0) {
        try {
        StockData arg1 = (StockData) arg0;
        if (id == arg1.id)
            return true;
        } catch (Exception e) {
        return false;
    }
    return false;
    }

    public void setDate(Calendar date) {
        this.date = date;
    }
    public Calendar getDate() {
    return date;
    }
    public void setId(int id) {
    this.id = id;
        }
        public int getId() {
            return id;
    }


    public void setShares(List<ShareBean> shares) {
    this.shares = shares;
    }

    public List<ShareBean> getShares() {
    return shares;
    }

public String toString(){
    String toReturn = "";
    toReturn+="ID: "+id+"\n";
    toReturn+="Date: "+date.getTime()+"\n";
    for(ShareBean share: shares)
        toReturn+="Shares: "+share.toString()+"\n";
    return toReturn;
}
}

Using this, you just make a StockData object for every datapiece you have, and add it to an array of such objects. Then, should you wish to find out if they are the same, you just use the .equals(Object arg0) method of StockData, and compare it to another StockData object.

For instance:

//this method compares to Lists of StockData, and returns a list containing all
//the StockData objects that had matches
public List<StockData> comparewithsecondarray(List<StockData> StockData1, List<StockData> StockData2) {
List<StockData> list = new ArrayList<StockData>();

for(StockData sd1: StockData1){
   for(StockData sd2: StockData2){
      if(sd1.equals(sd2)){
         //found a match!  add it to the list
         list.add(sd1);
         //break so we don't add the same object multiple times
         break;
      }
   }
}
return list;
}

It really looks like you have made this incredibly more complex than it needs to be. If you were to repost what SPECIFICALLY you want to do, it would make answering your question easier.

EDIT: I’ve modified my StockData class, and added this other class to keep track of shares:

public class ShareBean {
private String ticker;
private int shares;

public ShareBean(String ticker, int shares){
    this.ticker = ticker;
    this.shares = shares;
}

public void setTicker(String ticker) {
    this.ticker = ticker;
}
public String getTicker() {
    return ticker;
}
public void setShares(int shares) {
    this.shares = shares;
}
public int getShares() {
    return shares;
}


public String toString(){
    String toReturn = "";
    toReturn+="Ticker: "+ticker+", Shares: "+shares;
    return toReturn;
}
}

ANOTHER EDIT:

Put this main method somewhere… it doesn’t really matter.

public static void main(String[] args) {
    List<StockData> listSD1 = new ArrayList<StockData>();
    List<StockData> listSD2 = new ArrayList<StockData>();

    StockData sd1 = new StockData();
    StockData sd2 = new StockData();
    List<ShareBean> listShares1 = new ArrayList<ShareBean>();
    List<ShareBean> listShares2 = new ArrayList<ShareBean>();

    //create the shares for sd1
    listShares1.add(new ShareBean("goog", 3));
    listShares1.add(new ShareBean("ibm", 5));
    listShares1.add(new ShareBean("gs", 0));
    listShares1.add(new ShareBean("msft", 0));
    listShares1.add(new ShareBean("c", 1));

    //create the shares for sd2
    listShares2.add(new ShareBean("goog", 0));
    listShares2.add(new ShareBean("ibm", 1));
    listShares2.add(new ShareBean("gs", 3));
    listShares2.add(new ShareBean("msft", 0));
    listShares2.add(new ShareBean("c", 5));

    //set their ids
    sd1.setId(1);
    sd2.setId(2);

    //set the dates (using calendars)
    sd1.setDate(Calendar.getInstance());
    sd2.setDate(Calendar.getInstance());

    //and finally set the shares
    sd1.setShares(listShares1);
    sd2.setShares(listShares2);

    //now add each object to each list.  the lists will be exacly the same
    listSD1.add(sd1);
    listSD1.add(sd2);
    listSD2.add(sd1);
    listSD2.add(sd2);

    //now the lists are ready, and we can compare them
    //I put the comparewithsecondarray method in the StockData class, but it could go anywhere
    //I also overrode the "toString" method to make the output more readable (in both StockData and ShareBean)
    System.out.println(Arrays.toString(sd1.comparewithsecondarray(listSD1, listSD2).toArray()));
}