JFreeChart: DynamicTimeSeries with period of n milliseconds

Question

I\'m trying do define an interface in which I want to plot some values received by an external device. These values are received with a frequency that can be set through the

Answer 1

I think because you have this:

public class MultipleOfMilliseconds extends Millisecond
//                                          ^^^^^^^^^^^

this is true:

if(timeSample instanceof Millisecond)

If you change the ordering of the tests you might have better luck:

if(timeSample instanceof MultipleOfMillisecond)
  this.pointsInTime = new MultipleOfMillisecond[nMoments];
else if (timeSample instanceof Millisecond)
  this.pointsInTime = new Millisecond[nMoments];

Answer 2

Instead, use the original MilliDTSC & Millisecond, and invoke advanceTime() and append the old data as required before appending the new data. Using 200 ms as an example, do something like this:

float[] newData = new float[1];
float[] oldData = new float[1];

@Override
public void actionPerformed(ActionEvent e) {
    newData[0] = randomValue();
    oldData[0] = newData[0];
    for (int i = 0; i < 200; i++) {
        dataset.advanceTime();
        dataset.appendData(oldData);
    }
    dataset.appendData(newData);
}

Note that there are now 5 samples/second, spaced 200 ms apart.

Answer 3

This is the solution I implemented. I reported only the methods that I changed. It was a stupid error :D

public MilliDTSC(int nSeries, int nMoments, RegularTimePeriod timeSample) {
  super(nSeries, nMoments, timeSample);
  if(timeSample instanceof MultipleOfMillisecond){
    this.pointsInTime = new MultipleOfMillisecond[nMoments];
  }else if (timeSample instanceof Millisecond) {
    this.pointsInTime = new Millisecond[nMoments];
  } 
}

public class MultipleOfMillisecond extends Millisecond {

  private static final long serialVersionUID = 1L;
  private int periodMs = 100;

  public MultipleOfMillisecond(int periodMs){
    super();
    this.periodMs = periodMs;
  }

  public MultipleOfMillisecond(int periodMs, int millisecond, Second second){
    super(millisecond, second);
    this.periodMs = periodMs;
  }

  @Override
  public RegularTimePeriod next() {
    
    RegularTimePeriod result = null;
    if(getMillisecond() + periodMs <= LAST_MILLISECOND_IN_SECOND){
        result = new MultipleOfMillisecond( periodMs, (int)(getMillisecond() + periodMs), getSecond());
    }else{
        Second next = (Second)getSecond().next();
        if(next != null){
            result = new MultipleOfMillisecond(periodMs, (int)(getMillisecond() + periodMs - LAST_MILLISECOND_IN_SECOND - 1), next);
        }
    }
    return result;
    
  }

  @Override
  public RegularTimePeriod previous() {
    
    RegularTimePeriod result = null;
    if(getMillisecond() - periodMs >= FIRST_MILLISECOND_IN_SECOND){
        result = new MultipleOfMillisecond(periodMs, (int)getMillisecond() - periodMs, getSecond());
    }else{
        Second previous = (Second)getSecond().previous();
        if(previous != null){
            result = new MultipleOfMillisecond(periodMs, (int)(getMillisecond() - periodMs + LAST_MILLISECOND_IN_SECOND + 1), previous);
        }
    }
    return result;
    
  } 
}

Now I have 10 samples in 5 seconds, i set the period to 500 ms