MPAndroidChart multiple real time line chart - entries not added at correct xIndex - mpandroidchart

Question

I modified a little bit the Real Time Line Chart example to show two LineChart like the code below.
Problem: the ViewPort is moving incorrectly does not work properly. It is moving much faster than real points (Entry) are added. In other words, the Entry get added in the wrong place and the ViewPort keeps moving right uncontrollably. It should move right only gradually as each Entry is added. Please help me to fix this one.
private int year = 2015;
SimpleDateFormat sdf = new SimpleDateFormat("hh:mm:ss.SSS");
private int[] mColors = {Color.BLUE,Color.YELLOW,Color.CYAN,Color.MAGENTA,Color.GREEN};
private int mCurrentColorIndex = 0;
private synchronized void addEntry(String id, float value) {
LineData data = mChart.getData();
if (data != null) {
ILineDataSet set = data.getDataSetByLabel(id,true);
//ILineDataSet set1 = data.getDataSetByIndex(0);
if (set == null) {
set = createSet(id, mColors[(mCurrentColorIndex++)%mColors.length ]);
data.addDataSet(set);
}
String xValue = sdf.format(new Date());
// add a new x-value first
data.addXValue(xValue);
set.addEntry(new Entry(value, set.getEntryCount(), 0));
// let the chart know it's data has changed
mChart.notifyDataSetChanged();
// limit the number of visible entries
mChart.setVisibleXRangeMaximum(30);
// mChart.setVisibleYRange(30, AxisDependency.LEFT);
// move to the latest entry
mChart.moveViewToX(data.getXValCount() - 31);
// this automatically refreshes the chart (calls invalidate())
// mChart.moveViewTo(data.getXValCount()-7, 55f,
// AxisDependency.LEFT);
}
}
private LineDataSet createSet(String label, int color) {
LineDataSet set = new LineDataSet(null, label);
set.setAxisDependency(AxisDependency.LEFT);
set.setColor(color);
set.setCircleColor(Color.WHITE);
set.setLineWidth(2f);
set.setCircleRadius(4f);
set.setFillAlpha(65);
set.setFillColor(color);
set.setHighLightColor(Color.rgb(244, 117, 117));
set.setValueTextColor(Color.WHITE);
set.setValueTextSize(9f);
set.setDrawValues(false);
return set;
}
private void feedMultiple() {
new Thread(new Runnable() {
#Override
public void run() {
for(int i = 0; i < 50; i++) {
runOnUiThread(new Runnable() {
#Override
public void run() {
addEntry("name1", (float)(Math.random() * 40) + 30f);
}
});
try {
Thread.sleep(35);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}).start();
new Thread(new Runnable() {
#Override
public void run() {
for(int i = 0; i < 100; i++) {
runOnUiThread(new Runnable() {
#Override
public void run() {
addEntry("name2", (float)(Math.random() * 40) + 30f);
}
});
try {
Thread.sleep(35);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}).start();
}

Answer 1

Resolved in the comments by #Tony with the following change:
//set.addEntry(new Entry(value, set.getEntryCount(), 0)); //incorrect
set.addEntry(new Entry(value, data.getXValCount(), 0)); //correct
Explanation:
A LineData is composed of multiple ILineDataSet:
set.getEntryCount() returns the number of y-values in one DataSet and is effectively equivalent to yvals.size().
data.getXValCount() returns the total number of x-values the ChartData object represents.
Since we wish to add an entry at the last x-index, we should use data.getXValCount()
NOTE:
In MPAndroidCharts 3.0.1 data.getXValCount() is no longer present. You can instead use data.getXMax() + 1 instead.