I can't solve this MPAndroidChart null object reference error

Question

I am trying to create a pie chart from the data stored in the database using MPAndroidChart . The size of the database is not fixed so it might have 2 to 7 data.

This is how I'm taking the data from the database.

 myDb = new DatabaseHelper(this);
    Cursor pie = myDb.showKharcha();

    String[] xData = new String[pie.getCount()];
    float[] yData = new float[pie.getCount()];

    int i = 0;
    float total = 0;
    while (pie.moveToNext()){
        String kname = pie.getString(1);
        Float kh= pie.getFloat(2);
        float kharcha = kh.floatValue();
        total = total + kharcha ;

        xData[i]=kname;
        yData[i]=kharcha;
        i++;


    }

And this is the part of using the data for pie chart.

    ArrayList<PieEntry> yEntry= new ArrayList<>();
    ArrayList<String> xEntry = new ArrayList<>();

    for( i =0;i < yData.length;i++){
        yData[i] = yData[i]*100/total;
        yEntry.add(new PieEntry(yData[i],i));
    }

    for(i =0;i < xData.length;i++){

        xEntry.add(xData[i]);
    }

The error I get is null pointer exception error and this to be exact

Attempt to invoke virtual method 'void com.github.mikephil.charting.charts.PieChart.setRotationEnabled(boolean)' on a null object reference

The part containing setRotationEnabled(boolean) is as follows which is before calling the addDataSet method where everything I've provided takes place.

 protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);
setContentView(R.layout.piechart);
Log.d(TAG, "onCreate: starting to create chart");

pieChart.setRotationEnabled(true);
pieChart.setHoleRadius(25f);
pieChart.setTransparentCircleAlpha(0);
pieChart.setCenterText("Kharcha");
pieChart.setCenterTextSize(10);


addDataSet();}

I think I'm not being able to pass the float data to be used in a piechart. Any help would be appreciated.

Answer 1

you forgot to get the PieChart from the layout

pieChart = (PieChart) findViewById(R.id.chart1) ;