public BarData(ArrayList xVals, BarDataSet dataSet) {
super(xVals, toArrayList(dataSet));
}
使用案例：
ArrayList xVals= new ArrayList();
xVals.add("");
xVals.add("");
...
BarData barData = new BarData(xVals, dataSet);
mBarChart.setData(barData);
mBarChart.invalidate();
mBarChart.animateY(1000);

权宜之计：
xVals.add(" ");