Understand JavaFX UI Concept: Stage, Scene & Pane

JavaFX is a Java library that is used for developing desktop applications. It is a part of the Java Foundation Classes (JFC) and is designed to provide a lightweight, hardware-accelerated Java GUI.

The Stage class in JavaFX represents the top-level container for a scene graph. A Scene object is a container for all content in a scene graph. The Pane class is a layout container that allows you to position and resize children nodes in a flexible way.

In JavaFX, the Stage class acts as the top-level container for all components in a scene graph. It is responsible for managing the window in which the application’s user interface is displayed.

The Scene class represents the content of a scene graph, and it is where all of the visual elements of an application are placed.

The Pane class is a layout container that allows you to position and resize children nodes in a flexible way.

Together, these three classes form the foundation of the JavaFX API, and they are used to create and manage the graphical user interface (GUI) of a JavaFX application.

The Stage in JavaFX

The Stage class in JavaFX represents the top-level container for a scene graph. It is the root of the scene graph, which is the hierarchical structure that represents the visual elements of an application.

The Stage class is responsible for managing the window in which the application’s user interface is displayed.

In JavaFX, a stage can be thought of as the window that contains all of the content for a particular scene.

A Stage object has a Scene object associated with it, which is where the visual elements of the application are placed.

Here is an example of creating and showing a Stage in JavaFX:

// Create the stage
Stage stage = new Stage();

// Set the title of the stage
stage.setTitle("My JavaFX Application");

// Create a scene
Scene scene = new Scene(...);

// Set the scene on the stage
stage.setScene(scene);

// Show the stage
stage.show();

In this example, a new Stage object is created and a Scene object is associated with it.

The Scene is then set on the Stage and the Stage is shown to the user. This will create a window with the specified title and display the content of the Scene inside it.

The Scene in JavaFX

In JavaFX, the Scene class represents the content of a scene graph, which is the hierarchical structure that represents the visual elements of an application.

A Scene object is a container for all of the content in a scene graph. This can include visual elements such as shapes, controls, and images, as well as layout containers such as Pane and Group objects.

Here is an example of creating and setting a Scene object in JavaFX:

// Create the stage
Stage stage = new Stage();

// Create a scene
Scene scene = new Scene(...);

// Set the scene on the stage
stage.setScene(scene);

In this example, a new Scene object is created and then set on the Stage object using the setScene method.

This will cause the content of the Scene to be displayed inside the window managed by the Stage.

The Scene class also provides various methods for configuring the properties of the scene, such as its size, background color, and cursor.

These methods can be used to customize the appearance and behavior of the scene to suit the needs of your application.

The Pane in JavaFX

In JavaFX, the Pane class is a layout container that allows you to position and resize children nodes in a flexible way. It is a part of the JavaFX API and is used to organize the visual elements of a scene graph.

The Pane class provides several layout algorithms that determine how the children nodes are positioned and sized within the container. Some of the commonly used layout algorithms are:

• BorderPane: divides the container into five areas (top, bottom, left, right, and center) and allows you to position children nodes in each of these areas.
• FlowPane: arranges children nodes in a horizontal or vertical flow, wrapping at the edges of the container.
• GridPane: arranges children nodes in a grid of rows and columns.
• TilePane: arranges children nodes in a grid of equal-sized tiles.

Here is an example of using a Pane to lay out children nodes in a scene:

// Create a pane
Pane pane = new Pane();

// Add some children nodes to the pane
pane.getChildren().addAll(node1, node2, node3);

// Create a scene and set the pane as its root node
Scene scene = new Scene(pane);

In this example, a new Pane object is created and some children nodes are added to it.

The Pane is then used as the root node of the Scene, which means that it will be the top-level container for the visual elements in the scene.

The layout algorithm used by the Pane will determine the position and size of the children nodes within the container.

The Pane class also provides various methods for configuring the layout of the children nodes, such as setting the padding and spacing between the nodes.

These methods can be used to customize the appearance and behavior of the layout to suit the needs of your application.

The connection among Stage, Scene & Pane in JavaFX

In JavaFX, a stage is a container for a scene, which is a container for the user interface controls and visual elements that make up the display.

A pane is a container for holding and organizing the user interface controls and other visual elements that make up a scene.

A stage represents the top-level container for a JavaFX application, and it is where the user’s interaction with the application takes place.

The stage contains a scene, which is the container for all of the visual elements of the user interface, including controls, shapes, and other elements.

A pane is a container that is used to hold and organize the user interface controls and other visual elements that make up a scene.

A pane can be used to layout and organize the controls and elements in a scene, allowing the developer to control the position and size of each element.

In summary, the relationship between a stage, a scene, and a pane in JavaFX is that a stage contains a scene, and a scene contains one or more panes, which are used to layout and organize the controls and other visual elements in the scene.

Kent Wynn

Here is an example that shows how a stage, scene, and pane are related in JavaFX:

// Create the stage, which is the top-level container for the application
Stage stage = new Stage();

// Create a scene, which is the container for the user interface controls and visual elements
Scene scene = new Scene(500, 500);

// Create a pane, which is a container for holding and organizing the user interface controls and visual elements
Pane pane = new Pane();

// Add some controls and visual elements to the pane
Button button = new Button("Click me!");
pane.getChildren().add(button);

// Set the scene to use the pane as its root node
scene.setRoot(pane);

// Set the stage to use the scene as its content
stage.setScene(scene);

// Show the stage to make it visible to the user
stage.show();

In this example, a stage is created and a scene is added to it. The scene is then given a pane as its root node, which is used to layout and organize the user interface controls and other visual elements. Finally, the stage is shown to make it visible to the user.