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A bar chart is used to represent grouped data using rectangular bars. The length of these bars depicts the values. The bars in the bar chart can be plotted vertically or horizontally.
Following is a bar chart, comparing various car brands.
Bar Chart in JavaFX
In JavaFX, a Bar chart is represented by a class named BarChart. This class belongs to the package javafx.scene.chart. By instantiating this class, you can create an BarChart node in JavaFX.
To generate a bar chart in JavaFX, follow the steps given below.
Step 1: Defining the Axis
In the start() method of Application class, define the X and Y axis of the bar chart and set labels to them. In our example, X axis represents the category of comparison and the y axis represents the score.
public class ClassName extends Application {
@Override
public void start(Stage primaryStage) throws Exception {
//Defining the x axis
CategoryAxis xAxis = new CategoryAxis();
xAxis.setCategories(FXCollections.<String>observableArrayList(Arrays.asList(
"Speed", "User rating", "Milage", "Safety")));
xAxis.setLabel("category");
//Defining the y axis
NumberAxis yAxis = new NumberAxis();
yAxis.setLabel("score");
}
}
Step 2: Creating the Bar Chart
Create a line chart by instantiating the class named BarChart of the package javafx.scene.chart. To the constructor of this class, pass the objects representing the X and Y axis created in the previous step.
//Creating the Bar chart
BarChart<String, Number> barChart = new BarChart<>(xAxis, yAxis);
barChart.setTitle("Comparison between various cars");
Step 3: Preparing the Data
Instantiate the XYChart.Series class and add the data (a series of, x and y coordinates) to the Observable list of this class as follows −
//Prepare XYChart.Series objects by setting data
XYChart.Series<String, Number> series1 = new XYChart.Series<>();
series1.setName("Fiat");
series1.getData().add(new XYChart.Data<>("Speed", 1.0));
series1.getData().add(new XYChart.Data<>("User rating", 3.0));
series1.getData().add(new XYChart.Data<>("Milage", 5.0));
series1.getData().add(new XYChart.Data<>("Safety", 5.0));
XYChart.Series<String, Number> series2 = new XYChart.Series<>();
series2.setName("Audi");
series2.getData().add(new XYChart.Data<>("Speed", 5.0));
series2.getData().add(new XYChart.Data<>("User rating", 6.0));
series2.getData().add(new XYChart.Data<>("Milage", 10.0));
series2.getData().add(new XYChart.Data<>("Safety", 4.0));
XYChart.Series<String, Number> series3 = new XYChart.Series<>();
series3.setName("Ford");
series3.getData().add(new XYChart.Data<>("Speed", 4.0));
series3.getData().add(new XYChart.Data<>("User rating", 2.0));
series3.getData().add(new XYChart.Data<>("Milage", 3.0));
series3.getData().add(new XYChart.Data<>("Safety", 6.0));
Step 4: Add Data to the Bar Chart
Add the data series prepared in the previous step to the bar chart as follows −
//Setting the data to bar chart barChart.getData().addAll(series1, series2, series3);
Step 5: Creating a Group Object
In the start() method, create a group object by instantiating the class named Group. This belongs to the package javafx.scene.
Pass the BarChart (node) object, created in the previous step as a parameter to the constructor of the Group class. This should be done in order to add it to the group as follows −
Group root = new Group(barChart);
Step 6: Launching Application
Lastly, follow the given steps below to launch the application properly −
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Firstly, instantiate the class named Scene by passing the Group object as a parameter value to its constructor. To this constructor, you can also pass dimensions of the application screen as optional parameters.
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Then, set the title to the stage using the setTitle() method of the Stage class.
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Now, a Scene object is added to the stage using the setScene() method of the class named Stage.
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Display the contents of the scene using the method named show().
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Lastly, the application is launched with the help of the launch() method.
Example
The following example depicts various car statistics with the help of a bar chart. Following is a list of car brands along with their different characteristics, which we will show using a bar chart −
| Car | Speed | User Rating | Millage | Safety |
|---|---|---|---|---|
| Fiat | 1.0 | 3.0 | 5.0 | 5.0 |
| Audi | 5.0 | 6.0 | 10.0 | 4.0 |
| Ford | 4.0 | 2.0 | 3.0 | 6.0 |
Following is a Java program which generates a bar chart, depicting the above data using JavaFX.
Save this code in a file with the name BarChartExample.java.
import java.util.Arrays;
import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.chart.BarChart;
import javafx.scene.chart.CategoryAxis;
import javafx.stage.Stage;
import javafx.scene.chart.NumberAxis;
import javafx.scene.chart.XYChart;
public class BarChartExample extends Application {
@Override
public void start(Stage stage) {
//Defining the axes
CategoryAxis xAxis = new CategoryAxis();
xAxis.setCategories(FXCollections.<String>
observableArrayList(Arrays.asList("Speed", "User rating", "Milage", "Safety")));
xAxis.setLabel("category");
NumberAxis yAxis = new NumberAxis();
yAxis.setLabel("score");
//Creating the Bar chart
BarChart<String, Number> barChart = new BarChart<>(xAxis, yAxis);
barChart.setTitle("Comparison between various cars");
//Prepare XYChart.Series objects by setting data
XYChart.Series<String, Number> series1 = new XYChart.Series<>();
series1.setName("Fiat");
series1.getData().add(new XYChart.Data<>("Speed", 1.0));
series1.getData().add(new XYChart.Data<>("User rating", 3.0));
series1.getData().add(new XYChart.Data<>("Milage", 5.0));
series1.getData().add(new XYChart.Data<>("Safety", 5.0));
XYChart.Series<String, Number> series2 = new XYChart.Series<>();
series2.setName("Audi");
series2.getData().add(new XYChart.Data<>("Speed", 5.0));
series2.getData().add(new XYChart.Data<>("User rating", 6.0));
series2.getData().add(new XYChart.Data<>("Milage", 10.0));
series2.getData().add(new XYChart.Data<>("Safety", 4.0));
XYChart.Series<String, Number> series3 = new XYChart.Series<>();
series3.setName("Ford");
series3.getData().add(new XYChart.Data<>("Speed", 4.0));
series3.getData().add(new XYChart.Data<>("User rating", 2.0));
series3.getData().add(new XYChart.Data<>("Milage", 3.0));
series3.getData().add(new XYChart.Data<>("Safety", 6.0));
//Setting the data to bar chart
barChart.getData().addAll(series1, series2, series3);
//Creating a Group object
Group root = new Group(barChart);
//Creating a scene object
Scene scene = new Scene(root, 600, 400);
//Setting title to the Stage
stage.setTitle("Bar Chart");
//Adding scene to the stage
stage.setScene(scene);
//Displaying the contents of the stage
stage.show();
}
public static void main(String args[]){
launch(args);
}
}
Compile and execute the saved java file from the command prompt using the following commands.
javac --module-path %PATH_TO_FX% --add-modules javafx.controls BarChartExample.java java --module-path %PATH_TO_FX% --add-modules javafx.controls BarChartExample
Output
On executing, the above program generates a JavaFX window displaying an area chart as shown below.
Example
The following table depicts the number of fruits consumed by John and Jane in a week.
| Day of the Week | Fruits consumed by John | Fruits consumed by Jane |
|---|---|---|
| Monday | 3 | 1 |
| Tuesday | 4 | 3 |
| Wednesday | 3 | 4 |
| Thursday | 5 | 3 |
| Friday | 4 | 3 |
| Saturday | 10 | 5 |
| Sunday | 12 | 4 |
Following is a Java program which generates an bar chart, depicting the above data using JavaFX.
Save this code in a file with the name BarChartFruits.java.
import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.chart.BarChart;
import javafx.scene.chart.CategoryAxis;
import javafx.stage.Stage;
import javafx.scene.chart.NumberAxis;
import javafx.scene.chart.XYChart;
public class BarChartFruits extends Application {
@Override
public void start(Stage stage) {
//Defining the X axis
CategoryAxis xAxis = new CategoryAxis();
//defining the y Axis
NumberAxis yAxis = new NumberAxis(0, 15, 2.5);
yAxis.setLabel("Fruit units");
//Creating the Area chart
BarChart<String, Number> barChart = new BarChart(xAxis, yAxis);
barChart.setTitle("Average fruit consumption during one week");
//Prepare XYChart.Series objects by setting data
XYChart.Series series1 = new XYChart.Series();
series1.setName("John");
series1.getData().add(new XYChart.Data("Monday", 3));
series1.getData().add(new XYChart.Data("Tuesday", 4));
series1.getData().add(new XYChart.Data("Wednesday", 3));
series1.getData().add(new XYChart.Data("Thursday", 5));
series1.getData().add(new XYChart.Data("Friday", 4));
series1.getData().add(new XYChart.Data("Saturday", 10));
series1.getData().add(new XYChart.Data("Sunday", 12));
XYChart.Series series2 = new XYChart.Series();
series2.setName("Jane");
series2.getData().add(new XYChart.Data("Monday", 1));
series2.getData().add(new XYChart.Data("Tuesday", 3));
series2.getData().add(new XYChart.Data("Wednesday", 4));
series2.getData().add(new XYChart.Data("Thursday", 3));
series2.getData().add(new XYChart.Data("Friday", 3));
series2.getData().add(new XYChart.Data("Saturday", 5));
series2.getData().add(new XYChart.Data("Sunday", 4));
//Setting the XYChart.Series objects to area chart
barChart.getData().addAll(series1,series2);
//Creating a Group object
Group root = new Group(barChart);
//Creating a scene object
Scene scene = new Scene(root, 600, 400);
//Setting title to the Stage
stage.setTitle("Bar Chart");
//Adding scene to the stage
stage.setScene(scene);
//Displaying the contents of the stage
stage.show();
}
public static void main(String args[]){
launch(args);
}
}
Compile and execute the saved java file from the command prompt using the following commands.
javac --module-path %PATH_TO_FX% --add-modules javafx.controls BarChartFruits.java java --module-path %PATH_TO_FX% --add-modules javafx.controls BarChartFruits
Output
On executing, the above program generates a JavaFX window displaying an area chart as shown below.
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