问如何使用MPAndroidChart创建带分组条的BarChart？

EN

BarChart barChart = (BarChart) view.findViewById(R.id.chart);
barChart.setDrawBarShadow(false);
barChart.setDrawValueAboveBar(true);
barChart.setDescription("");
barChart.setMaxVisibleValueCount(50);
barChart.setPinchZoom(false);
barChart.setDrawGridBackground(false);

XAxis xl = barChart.getXAxis();
xl.setGranularity(1f);
xl.setCenterAxisLabels(true);
xl.setValueFormatter(new AxisValueFormatter() {
    @Override
    public String getFormattedValue(float value, AxisBase axis) {
        return String.valueOf((int) value);
    }

    @Override
    public int getDecimalDigits() {
        return 0;
    }
});

YAxis leftAxis = barChart.getAxisLeft();
leftAxis.setValueFormatter(new AxisValueFormatter() {
    @Override
    public String getFormattedValue(float value, AxisBase axis) {
        return String.valueOf((int) value);
    }

    @Override
    public int getDecimalDigits() {
        return 0;
    }
});
leftAxis.setDrawGridLines(false);
leftAxis.setSpaceTop(30f);
leftAxis.setAxisMinValue(0f); // this replaces setStartAtZero(true
barChart.getAxisRight().setEnabled(false);

//data
float groupSpace = 0.04f;
float barSpace = 0.02f; // x2 dataset
float barWidth = 0.46f; // x2 dataset
// (0.46 + 0.02) * 2 + 0.04 = 1.00 -> interval per "group"

int startYear = 1980;
int endYear = 1985;
List<BarEntry> yVals1 = new ArrayList<BarEntry>(); 
List<BarEntry> yVals2 = new ArrayList<BarEntry>();

for (int i = startYear; i < endYear; i++) {
    yVals1.add(new BarEntry(i, 0.4f));
    yVals2.add(new BarEntry(i, 0.7f));
}

BarDataSet set1, set2;
if (barChart.getData() != null && barChart.getData().getDataSetCount() > 0) {
    set1 = (BarDataSet)barChart.getData().getDataSetByIndex(0);
    set2 = (BarDataSet)barChart.getData().getDataSetByIndex(1);
    set1.setValues(yVals1);
    set2.setValues(yVals2);
    barChart.getData().notifyDataChanged();
    barChart.notifyDataSetChanged();
} else {
    // create 2 datasets with different types
    set1 = new BarDataSet(yVals1, "Company A");
    set1.setColor(Color.rgb(104, 241, 175));
    set2 = new BarDataSet(yVals2, "Company B");
    set2.setColor(Color.rgb(164, 228, 251));
    ArrayList<IBarDataSet> dataSets = new ArrayList<IBarDataSet>();
    dataSets.add(set1);
    dataSets.add(set2);
    BarData data = new BarData(dataSets);
    barChart.setData(data);
}

barChart.getBarData().setBarWidth(barWidth);
barChart.getXAxis().setAxisMinValue(startYear);
barChart.groupBars(startYear, groupSpace, barSpace);
barChart.invalidate();