How to Add a Button to a Window Using JavaFX

In this article, we show how to set the size of a window in JavaFX.

This way, we can control the width and height of a window.

The Java code to set the size of a window is shown below.

import javafx.application.Application; import javafx.event.ActionEvent; import javafx.event.EventHandler; import javafx.scene.Scene; import javafx.scene.control.Button; import javafx.scene.layout.StackPane; import javafx.stage.Stage; public class FirstGUI extends Application { @Override public void start(Stage primaryStage) { primaryStage.setTitle("My First JavaFX GUI"); StackPane layout= new StackPane(); Scene scene1= new Scene(layout, 300, 250); primaryStage.setScene(scene1); primaryStage.show(); } public static void main(String[] args) { launch(args); } }

So in order to start a JavaFX application, you have to import several javafx packages. These include definitions of objects, functions, etc. that is needed to create a JavaFX application.

The class name that you choose must extend Application. Thus, the class inherits everything from the Application class. In this Application class is a broad range of functions and tools needed to create a JavaFX application.

Inside of this application is a method named start().

What we do in our code is we want to override this start() method. This way, we can create our own custom window in JavaFX. The start() method can be seen as the heart of the JavaFX application because it is inside of this method, we add in all the code needed for the JavaFX window.

This start() method takes in the parameter, primaryStage.

The primaryStage represents the window, essentially. So it represents the window object.

We add a title, "My First JavaFX GUI" to the window.

We create a layout by creating an instance of the StackPane class. We name of the instance, layout.

We then create a scene. The stage is primaryStage. We now need to add a scene to this stage. Remember that in all JavaFX applications, one stage and one scene is required.

We create a scene by making an instance of the Scene class. We name this object, scene1. Into this new object, we pass in the parameters, (layout, 300,250). The layout variable shows how the scene is laid out. The second parameter is the width, which we set to 300 in this example. The third parameter is the length, which we set to 250 in this example. Thus, we have a layout with a button added, with the window set to a width of 300px and a length of 250px.

Thus, this is how we can set the size of a window in JavaFX.

We then use the setScene() function to set the scene of the primaryStage to scene1. This lets us add the scene to the stage.

We then show the stage.

And this is what is required to set the size of a window using JavaFX.

Related Resources

How to Add a Title to a Window Using JavaFX