How to use

setCategoryGap

method

in

javafx.scene.chart.BarChart

static BarChart<String, Number> getBarChart(String title, CategoryAxis categoryAxis, NumberAxis numberAxis) {
  BarChart<String, Number> bar = new BarChart<>(categoryAxis, numberAxis);
  bar.setTitle(title);
  bar.setLegendVisible(false);
  bar.setCategoryGap(0.0);
  bar.setBarGap(0.1);
  bar.setBackground(Background.EMPTY);
  bar.setVerticalGridLinesVisible(false);
  return bar;
}

  private static BarChart<Number, String> getNumberStringBarChart(String title, NumberAxis xAxis, CategoryAxis
      yAxis) {
    final BarChart<Number, String> bar = new BarChart<>(xAxis, yAxis);
    bar.setTitle(title);
    bar.setLegendVisible(false);
    bar.setCategoryGap(0.0);
    bar.setBarGap(0.25);
    bar.setBackground(Background.EMPTY);
    bar.setHorizontalGridLinesVisible(false);
    return bar;
  }
}

public static BarChart<String, Number> chart(
    String title,
    StringColumn x,
    NumberColumn y) {
  final CategoryAxis xAxis = new CategoryAxis();
  final NumberAxis yAxis = new NumberAxis();
  xAxis.setLabel(x.name());
  yAxis.setLabel(y.name());
  Table t = Table.create("", x, y);
  t = t.sortDescendingOn(y.name());
  final BarChart<String, Number> bar = new BarChart<>(xAxis, yAxis);
  bar.setTitle(title);
  List<XYChart.Data<String, Number>> d2 = new ArrayList<>(x.size());
  for (int i = 0; i < x.size(); i++) {
    d2.add(new XYChart.Data<>(t.stringColumn(0).get(i), t.nCol(1).get(i)));
  }
  XYChart.Series<String, Number> series1
      = new XYChart.Series<>(FXCollections.observableList(d2));
  series1.setName(y.name());
  bar.setLegendVisible(false);
  bar.setCategoryGap(0.0);
  bar.setBarGap(0.1);
  bar.setBackground(Background.EMPTY);
  bar.setVerticalGridLinesVisible(false);
  bar.getData().add(series1);
  return bar;
}