Question

The issue with my code is that when I call generateCSV() below, the output of the ArrayList is not correct. It is replacing all of the instances with only the last instance to be instantiated, i.e. the last instance is replacing all previous incidences.

My base class, PausePred, takes a string and an ArrayList

public class PausePred {

    private String predString;  // the keys preceding the pause
    private ArrayList<KSE> kseArr;  // the arraylist of KSEs comprising the PausePred

    public PausePred(String predStr) { 
        this.predString = predStr;
        kseArr = new ArrayList<KSE>();
    } 

    public void setKseArr(ArrayList<KSE> kseArr) {
        this.kseArr.addAll(kseArr);
    }

Within PausePred, I have a static method to create an array of PausePreds.

public static Collection<PausePred> parseKseArray(KSE[] kArr) {

    Collection<PausePred> pausePredArray = new ArrayList<PausePred>();

    String pausePredStr = "";       // to store incrementally appended events preceding pause
    int pauseDur = 0;               // to store pause duration
    boolean startPosSet = false;    // checks if startPos has been set
    ArrayList<KSE> pausePredKseArr = new ArrayList<KSE>();;


    for (int kseArrIdx = 0; kseArrIdx < kArr.length; kseArrIdx++) {
        if (kArr[kseArrIdx].isKeyPress()) { // only down-keys
            // if start positio"n has not been set, set it, and update flag
            // set time stamp, as well
            if (startPosSet == false) {
                startPosSet = true;
                // get first char of PredStr by going back one index
                if (kseArrIdx > 0) {
                    pausePredStr = VisualCharStream.vkCodetoString(kArr[kseArrIdx-1].getKeyCode());
                    pausePredKseArr.add(kArr[kseArrIdx-1]);
                }
            }

            if (kArr[kseArrIdx].getM_pauseMs() < PauseBursts.PAUSE) {   // is not a pause
                //append vkCode (to string) to pausePred
                pausePredStr += VisualCharStream.vkCodetoString(kArr[kseArrIdx].getKeyCode());
                pausePredKseArr.add(kArr[kseArrIdx]);
            }

            else {  // is a pause

                //start incrementing pause duration, until a non-pause is reached
                while (kArr[kseArrIdx].getM_pauseMs() >= PauseBursts.PAUSE) {
                    pauseDur = (int) kArr[kseArrIdx].getM_pauseMs();
                    kseArrIdx++;
                }

                //add to pausePred array
                PausePred pp = new PausePred(pausePredStr);
                pp.setKseArr(pausePredKseArr);
                pausePredArray.add(pp);

                //reset variables
                pausePredStr = "";
                startPosSet = false;
                pausePredKseArr.clear();
                //need to take one step back from above while loop
                kseArrIdx--;
            }
        } // close outer if loop
    } // close for loop
    return pausePredArray;
} // close parseKseArray()

When I call this method below, the first part gives each instance, but the second part gives only the kseArr of the last instance in the array.

    public static void generateCSV(String fileName,ArrayList<PausePred> pausePredArr) {
        for (PausePred pp : pausePredArr)
System.out.println(pp.getPredString()+"\t"+pp.kseArr.get(pp.kseArr.size()-1).getKeyCode()); 
}

This is the extraction method that calls the parse method above. I’m not sure if it’s germane to this issue.

public class ExtractPausePred implements ExtractionModule {

    private static ArrayList<PausePred> pausePredArray = new ArrayList<PausePred>();

    @Override
    public void extract(DataNode data) {

        for (Answer a : data) {
            //create KSE array
            KSE[] kseArr = parseSessionToKSE(a.getKeyStrokes());

            //from above KSE array, extract Pause Predecessors
            pausePredArray.addAll(PausePred.parseKseArray(kseArr));
            PausePred.generateCSV("testing123",pausePredArray);
        }

        return null;
    }
}

Answer 1

The problem is your attempt to prematurely optimize by reusing the same objects:

pausePredKseArr.clear();

Create a new ArrayList instead of clearing the old one and you’ll be fine.