CS1021 - JavaFX

name: inverse
layout: true
class: taylor msoe
---
class: center, middle

.title[
  # JavaFX
  ## Graphical User Interfaces
]

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* **P** speaker view
* **C** clone slideshow
* **?** help

---
# `Application` Class
* Create a JavaFX application by extending the [`Application`](https://openjfx.io/javadoc/11/javafx.graphics/javafx/application/Application.html) class

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* Implement the abstract `start()` method

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* A class **must** be declared abstract if it has one or more abstract methods

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* `start(Stage stage)` method is passed a reference to a [`Stage`](https://openjfx.io/javadoc/11/javafx.graphics/javafx/stage/Stage.html) object

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* The `Stage` represents the application window

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    + `setScene(Scene scene)` - set the scene of the stage
    + `show()` - makes the window visible

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# Example

.left-column[
![Hello World](rev4-2a.png)
]
.right-column[
```
public class HelloWorld extends Application {

@Override
    public void start(Stage stage) {
        Label label = new Label("Hello World!");
        label.setFont(new Font(40));
        Scene scene = new Scene(label);

stage.setTitle("Welcome to JavaFX!");
        stage.setScene(scene);
        stage.show();
    }

public static void main(String[] args) {
        Application.launch(args);
    }
}
```
]
---
# `Scene` Class
* The [`Scene`](https://openjfx.io/javadoc/11/javafx.graphics/javafx/scene/Scene.html) class is the container for the scene graph

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* Must set a root [`Node`](https://openjfx.io/javadoc/11/javafx.graphics/javafx/scene/Node.html)
--

+ Could be a **leaf** node with no additional nodes
--
        - (e.g., a [`Shape`](https://openjfx.io/javadoc/11/javafx.graphics/javafx/scene/shape/Shape.html) - [`Line`](https://openjfx.io/javadoc/11/javafx.graphics/javafx/scene/shape/Line.html), [`Circle`](https://openjfx.io/javadoc/11/javafx.graphics/javafx/scene/shape/Circle.html), [`Rectangle`](https://openjfx.io/javadoc/11/javafx.graphics/javafx/scene/shape/Rectangle.html), ...)
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    + Could be a **branch** node with additional nodes - child of [`Parent`](https://openjfx.io/javadoc/11/javafx.graphics/javafx/scene/Parent.html) class
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        - [`Group`](https://openjfx.io/javadoc/11/javafx.graphics/javafx/scene/Group.html) - contains a list of children
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        - [`WebView`](https://openjfx.io/javadoc/11/javafx.web/javafx/scene/web/WebView.html) - manages a [`WebEngine`](https://openjfx.io/javadoc/11/javafx.web/javafx/scene/web/WebEngine.html) and displays its content
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        - [`Pane`](https://openjfx.io/javadoc/11/javafx.graphics/javafx/scene/layout/Pane.html) - base class for layout panes
        - [`FlowPane`](https://openjfx.io/javadoc/11/javafx.graphics/javafx/scene/layout/FlowPane.html) - lays out its children in a flow that wraps at the flowpane's boundary

---
# Adding to a Pane
.pull-right[
![Teenager](rev4-2b.png)
]
```
public class Teenager extends Application {
    private Label response;
    public static final int HEIGHT = 200;
    public static final int WIDTH = 300;

@Override
    public void start(Stage stage) {
        response = new Label();
        TextField input = new TextField();
        Button clear = new Button("Clear");

Pane pane = new FlowPane();
*       pane.getChildren().add(new Label("Please enter your age: "));
*       pane.getChildren().add(input);
*       pane.getChildren().add(response);
*       pane.getChildren().add(clear);

stage.setScene(new Scene(pane, WIDTH, HEIGHT));
        stage.show();
    }
}
```

---
# Setting Actions
```
    @Override
    public void start(Stage stage) {
        // ...
        // ...
        // ...
        pane.getChildren().add(clear);

*       input.setOnAction(this::enterPressed);
*       clear.setOnAction(this::clearPressed);

stage.setScene(scene);
        stage.show();
    }

*   private void clearPressed(ActionEvent actionEvent) {
*       response.setText("");
*   }
```

---
# Setting Actions continued
```
    private void enterPressed(ActionEvent actionEvent) {
        String text = ((TextField)actionEvent.getSource()).getText();
        int age = Integer.parseInt(text);
        String not = "";
        if(age<13 || age>19) {
            not = "not ";
        }
        response.setText("You are " + not + "a teenager.");
    }
```

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# Alternative to `parseInt()`
```
    private void enterPressedRobust(ActionEvent actionEvent) {
        String text = ((TextField)actionEvent.getSource()).getText();
        Scanner parser = new Scanner(text);
*       if(parser.hasNextInt()) {
*           int age = parser.nextInt();
            boolean isTeenager = age>12 && age<20;
            response.setText("You are " + (isTeenager ? "" : "not ") + "a teenager");
*       } else {
*           response.setText("Please enter an integer");
*       }
    }
```