How to Re-Write the graph in a Graphview without getting the extra line?

I'm trying to plot the value in GraphView and for 2nd time i'm trying plot the another set of data in the same graphview but I'm getting some extra unwanted line in the graphview.

in the above picture Red colored marked line is the extra line I'm getting while plotting the graph.

I'm using com.jjoe64.graphview.GraphView

Here is my sample code , when ever i click on OK button it will start plotting the graph.

public class ABIModeActivity extends AppCompatActivity {

private LineGraphSeries<DataPoint> mSeries2;
private double graph2LastXValue = 5d;
static GraphView graph2;
Context context;
Button okbutton;
CountDownTimer cTimer = null;
int i=0;
int[] BP_Data=new int[]{115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,115,113,105,76,36,7,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,7,33,73,105,112,114,113,84,32,22,5,1,0,0,0,0,0,1,8,37,76,95,112,111,90,51,12,2,0,0,0,0,2,21,59,83,105,113,112,105,62,48,17,2,7,33,73,105,112,114,113,84,32,22,5,1,0,0,0,0,0,1,8,37,76,95,112,111,90,51,12,2,0,2,21,59,83,105,113,112,105,62,48,17,2,2,21,59,83,105,113,112,105,62,48,17,2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    getSupportActionBar().hide();
    setContentView(R.layout.activity_abimode);

    //I'm using Timer to simulate the live data graph which I'm getting in my actual device.
    //Timer is used only for simulation of live data
    cTimer = new CountDownTimer(100000, 20) {
        public void onTick(long millisUntilFinished) {
            graph2LastXValue += 1d;
            drawgraph(graph2LastXValue,BP_Data[i]);
            i++;
            if(i==180){
                cTimer.cancel();//Stop the live graph plotting when it reached the end of data
                i=0;
            }
        }
        public void onFinish() {

        }
    };

    okbutton =(Button) findViewById(R.id.okbutton);
    okbutton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view)
        {
            cTimer.start();// to start plotting the graph data with the timer
        }
    });
    //Actuall graph realted code starting
    graph2 = (GraphView) findViewById(R.id.graph2);
    mSeries2 = new LineGraphSeries<>();
    mSeries2.setThickness(3);
    graph2.getViewport().setXAxisBoundsManual(true);
    graph2.getViewport().setYAxisBoundsManual(true);
    graph2.getViewport().setMinX(0);
    graph2.getViewport().setMaxX(200);
    graph2.getViewport().setMinY(0);
    graph2.getViewport().setMaxY(251);
    graph2.getGridLabelRenderer().setTextSize(0);
    graph2.getViewport().setScrollable(true); // enables horizontal scrolling
    graph2.getViewport().setScrollableY(true); // enables vertical scrolling
    graph2.getViewport().setDrawBorder(false);
    graph2.getViewport().setBackgroundColor(Color.TRANSPARENT);
    graph2.addSeries(mSeries2);
    context = this;
}

public void drawgraph(Double graphvalue,int incrementValue)//plotting the value in the graph
{
    mSeries2.appendData(new DataPoint(graphvalue, incrementValue), true, 200);
}

}

Solution

If you need a newly drawn graph everytime you press the button, you need to add the following change to your onTick method:

@Override
public void onTick(long millisUntilFinished) {
    graph2LastXValue += 1d;
    if (i == 0) {
        mSeries2.resetData(new DataPoint[]{new DataPoint(graph2LastXValue, BP_Data[i])});
    }
    drawgraph(graph2LastXValue, BP_Data[i]);
    i++;
    if (i == 180) {
        cTimer.cancel();//Stop the live graph plotting when it reached the end of data
        i = 0;
    }
}

This will reset your graph every time the value of i has been reset earlier and gives you the desired result.