How to set the x-axis label with MPAndroidChart

Question

I use MPAndroidChart for my app like this:

but I can not add tag like that

Answer 1

Do you need your tag instead of those values?

If so, then here it goes the method to do so.

Add your XAxis labels to an ArrayList

    final ArrayList<String> xLabel = new ArrayList<>();
    xLabel.add("9");
    xLabel.add("15");
    xLabel.add("21");
    xLabel.add("27");
    xLabel.add("33");  

    // or use some other logic to save your data in list. For ex. 
    for(i=1; i<50; i+=2)
    { 
       xLabel.add(""+3*i);
    }

then use this label in the setValueFormatter.
Ex:

    XAxis xAxis = mChart.getXAxis();
    xAxis.setPosition(XAxis.XAxisPosition.BOTTOM);
    xAxis.setDrawGridLines(false);
    xAxis.setValueFormatter(new IAxisValueFormatter() {
        @Override
        public String getFormattedValue(float value, AxisBase axis) {
            return xLabel.get((int)value);
        }
    });

Result:

Answer 2

You can override AxisValueFormatter

i.e.:

xAxis.setValueFormatter(new AxisValueFormatter() {
            @Override
            public String getFormattedValue(float value, AxisBase axis) {
                return "YOUR_TEXT"; // here you can map your values or pass it as empty string
            }

            @Override
            public int getDecimalDigits() {
                return 0; //show only integer
            }
        });

You can pick center value of the group to map the group name, others are empty. that would be the easiest way.