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Thread: Java is resetting my variables to zero, and other mysterious things

  1. #1
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    Default Java is resetting my variables to zero, and other mysterious things

    I'm not a great programmer, but I've spent a lot time with this problem and I would greatly appreciate any help.

    So here's the idea:

    I run load() from a class called menu. load() is located in a class called astock(). load() collects data from a file and loads it into an array called data of objects called stockdays. stockday is a class I wrote containing some doubles and integers.

    Then while loading this data, I examine it to see if price changes on different days meet threshold values set in menu.

    The crazy thing is, if I don't include the line: data[i].direction = 0; (marked by *** below) right before I run if-statements to examine price changes I get this behavoir:
    each data[i].direction is equal to data[i-1].direction (the previously analyzed piece). For example, if the thresholds are met and the if-statement runs then data.direction is changed and so if every single one afterwards even though in my constructor for stockday I explicitly state direction = 0 (initialization really).

    This problem is fixed if I include the ***'d line, but then I arrive at another problem.
    In the next method run called posJumpEx() every single data[].direction is equal to zero.

    I've written my stockday class with public variables. This may be bad form, I was just looking for a way to easily modify them. Could this be the problem?

    I'm going to attach my code below, I apologize it's so long, but I just cant seem to find a way to just post the explanatory parts:

    And it looks like all the tabs are screwed up, let me know if an email of the txt files would help. Thanks!

    \\_____HERE is the stockday class________
    public class stockday
    	public double
    	public long
    	public int
    				direction; // 0 unassigned, 1 negative, 2 positive
    	public stockday (double fhigh, double flow, double fprice, long fvolume)			//Constructor
    		high	= fhigh;
    		low 	= flow;
    		price 	= fprice;
    		volume 	= fvolume;
    		direction = 0;
    \\__________Here is the astock class, it uses the stockday objects ______________
    public class astock
    	public String
    	public static int 
    	public stockday
    	public double
    	public counter			//Counts the pos and neg jumps
    	public astock(String fTicker, int fNumDays, double fpthresh, double fpthrlen, double fnthresh, double fnthrlen) {		//Constructor
    		data = new stockday[fNumDays];
    		ticker = fTicker;
    		numDays = fNumDays;
    		pthresh = fpthresh;
    		pthrlen = fpthrlen;
    		nthresh = fnthresh;
    		nthrlen = fnthrlen;
    		stockday sd = new stockday(0,0,0,0);
    		for(int i=0; i <numDays; i++) 	//Need to initialize all stockday objects in array data[]
    			data[i] = sd;
    		cpos = new counter();
    		cneg = new counter();
    	public void load() {																	//Loads and marks jump locations
    		counter c1 = new counter();		//Creates a counter
    		try {
    			FileInputStream gstream = new FileInputStream("C://Programming//StockData//" + ticker + ".txt");
    			DataInputStream stkIn = new DataInputStream(gstream);
    			String str;
    			double prevprice = 0; 			//yesterdays price
    			double pchg = 0;				//percentage change from yesterday
    			for (int i = 0; i < numDays; i++) {
    				str = stkIn.readLine();
    				String fields[] = str.split(",");
    				data[i].price = Double.parseDouble(fields[0]);
    				data[i].high = Double.parseDouble(fields[3]);
    				data[i].low = Double.parseDouble(fields[2]);
    				data[i].volume = Long.parseLong(fields[1]);
    				//System.out.println("price: " + data[i].price + "\tVolume: " + data[i].volume + "\tLow: " + data[i].low + "\tHigh: " + data[i].high);
    				//Determine % chg, then set directions
    		********data[i].direction = 0;  ********
    				if(i > 0)									//Make sure we're not in the first run of the loop
    					pchg = (data[i].price - prevprice)/prevprice;
    					if( pchg < nthresh && pchg > (nthresh+nthrlen)) {
    						data[i].direction = 1;
    						cneg.click();							//add one to the counter to determine number of jumps
    					if( pchg > pthresh && pchg < (pthresh+pthrlen)) {
    						data[i].direction = 2;
    				System.out.println("price change: " + pchg + "\tdirection: " + data[i].direction);
    				prevprice = data[i].price;
    		} catch (IOException e) {}
    		System.out.println("Number of Pos Jumps: " + cpos.get());
    	public void posJumpEx() {																	//Gets jump/correction magnitudes
    		double corrPerc[] = new double[cpos.get()+1];
    		int n=0;
    		for(int i=0; i < numDays; i++)
    			//System.out.println("Direction: " + data[i].direction);
    			if(data[i].direction == 2)
    					corrPerc[n] = (data[i+1].price - data[i].price)/data[i].price;
    					System.out.println("Correction %: " + corrPerc[n]);
    \\___________Here is the menu class_____________ vary straightforward
    public class menu {
    	private static double 
    				pthresh = .08,
    				pthrlen = .07,
    				nthresh = -.08,
    				nthrlen = -.07;
    	private static int 
    				numDays = 1249;
    	public static void main (String args[]) {
    		astock Fdata = new astock("CNX", numDays, pthresh, pthrlen, nthresh, nthrlen);
    Last edited by helloworld922; January 8th, 2010 at 11:29 PM. Reason: Please use [code] tags!

  2. #2
    Junior Member
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    Jan 2010
    Thanked 3 Times in 2 Posts

    Default Re: Java is resetting my variables to zero, and other mysterious things


    as you have suggested, its a bit difficult to read the files from here. can you attach the text files of the code
    and the input file that is in ur c drive,

    Moreover on glancing through the code your code looks fine. though i will need to run the program to see

    can you explain the exact problem when you *** line is not there, as i dont see any benefits of having and it also means that your data set wll be wrong as well

  3. The Following 2 Users Say Thank You to vkumar23 For This Useful Post:

    JavaPF (January 10th, 2010), schcrosby (January 12th, 2010)

  4. #3
    Junior Member
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    Default Re: Java is resetting my variables to zero, and other mysterious things

    I've attached all the code and the output with and without the **** line. I've also attached the data file that the code reads in. You'll have to change the file references in the code to make it work properly though.

    I'll try to do a better job explaining what happens.
    I'm try to identify particular jumps in price by certain thresholds and I'm trying to identify them with a variable called direction.
    direction = 0 for no jump, 1 for neg jump, and 2 for pos jump.

    I initialize direction = 0 in the constructor for stockday so by default there is no jump unless assigned in the load() function in astock.

    If I don't include that line and I examine direction I find that direction goes about as follows:

    00000000002222222222221111111112222222222222222211 111111111111
    where it should have been
    00000000002000000000001000000002000000000000000010 0000000000000

    I know that the if-statements are working because I get a reasonable number of counts via my counters

    If I do include that **** line I get what it should be. So in a way everything is fixed. But including that line doesn't make sense and furthermore I find a new problem in my function posJumpEx() as I go to examine all the jumps that should have been recorded. If the line is included every direction variable is zero.

    I realize this is hard to explain. I hope that what I've said helps. Thanks for taking a look!
    Attached Files Attached Files

  5. #4
    Junior Member
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    Default Re: Java is resetting my variables to zero, and other mysterious things

    Hi guys,
    So I've done some more debugging and discovered what java is doing, but I still don't know why.

    So what's happening is this:
    in astock.load()

    every time a new data element, data[i] is assigned a new value, every data[i] is assigned that value as well.

    For example, say i = 2,

    data[i].price = Double.parseDouble(fields[0]);

    what happens is instead of just data[2].price = 45.67, every price element in data[] is equal to 45.67

    I'm not familiar enough with java to figure out what this is happening. help would be most welcomed

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