XY LineChart, how to remove?

[susieferrari]

Hi all,

I have a simple serie plotted on a XY Line Chart as below

public class SimpleXYLineChart extends Application {

@Override
public void start(Stage stage) {        
   stage.setTitle("Line plot");       

   final CategoryAxis xAxis = new CategoryAxis();
   final NumberAxis yAxis = new NumberAxis(1, 22, 0.5);

   yAxis.setTickLabelFormatter(new NumberAxis.DefaultFormatter(yAxis){
        @Override
    public String toString(Number object){
        return String.format("%7.2f", object);
    }
});
    final LineChart<String, Number>lineChart = new LineChart<String, Number>(xAxis, yAxis);

    lineChart.setCreateSymbols(false);
    lineChart.setAlternativeRowFillVisible(false);
    lineChart.setLegendVisible(false);
    lineChart.setTitle("LineChart");

    XYChart.Series series1 = new XYChart.Series();

    series1.getData().add(new XYChart.Data("Jan", 1));
    series1.getData().add(new XYChart.Data("Feb", 1.5));
    series1.getData().add(new XYChart.Data("Mar", 2));
    series1.getData().add(new XYChart.Data("Apr", 2.5));
    series1.getData().add(new XYChart.Data("May", 3));
    series1.getData().add(new XYChart.Data("Jun", 4));
    series1.getData().add(new XYChart.Data("Jul", 6));
    series1.getData().add(new XYChart.Data("Aug", 9));
    series1.getData().add(new XYChart.Data("Sep", 12));
    series1.getData().add(new XYChart.Data("Oct", 15));
    series1.getData().add(new XYChart.Data("Nov", 20));
    series1.getData().add(new XYChart.Data("Dec", 22));

    lineChart.getData().addAll(series1);        

    Scene scene = new Scene(new Group(), 800, 600);
    final VBox vbox = new VBox();
    final HBox hbox = new HBox();

    final Button remove = new Button("Remove Series");
    remove.setOnAction(new EventHandler<ActionEvent>() {
        @Override public void handle(ActionEvent e) {
    if (!lineChart.getData().isEmpty()){
        System.out.println("Remove Series");
        lineChart.getData().remove((lineChart.getData().size()-1),0);
        }
}
    });                

    hbox.setSpacing(10);
    hbox.getChildren().addAll(remove);

    vbox.getChildren().addAll(lineChart, hbox);
    hbox.setPadding(new Insets(10, 10, 10, 50));

    ((Group)scene.getRoot()).getChildren().add(vbox);
    stage.setScene(scene);
    stage.show();
}

public static void main(String[] args) {
    launch(args);
}   
}

I would like to remove the line plotted by clicking on the "remove" button and have the empty scene as below



I have found this example for scatter plot

docs.oracle.com/javafx/2/charts/ScatterChartSample.java.html

and it works, I do not know why my example does not remove line plotted while the scatter plot does.

When I click on remove button I get Null Pointer Exception

Any help really appreciated

Susie

[DarrylBurke]

Consistent indentation would reveal this:

    remove.setOnAction(new EventHandler<ActionEvent>() {

        @Override
        public void handle(ActionEvent e) {
            if (!lineChart.getData().isEmpty()) 
                    System.out.println("Remove Series");
            lineChart.getData().remove(/*(lineChart.getData().size()-1)*/0);
        }
    });

The call to remove(...) is unconditional. Was that intended?

Always use braces around if/else/while blocks. That way, if you add a line later you won't mess up the program flow.

db

[susieferrari]

Hi Darryl,

I have correct the code above, but still remain my question: how to remove a Line in a XY Chart once plotted by clicking on a button?

Thanks

Susie

[DarrylBurke]

Are you still getting a NPE?

db

[susieferrari]

Are you still getting a NPE?

db

Having removed comment I do not have Null Pointer Exc but it does not remove the serie: I wonder why the scatter chart example works perfectly while my example do not.

Where am I wrong?

Susie

[susieferrari]

Ok found the problem, question now closed.

Susie

[susieferrari]

All the solved questions posted in this forum are implemented in my project

Advanced Market Forecast

Susie