Button

A Button in JavaFX is a UI control that the user can click to trigger an action.

Think of it like:

• “Submit”
• “Login”
• “Next”

When the user clicks it → something happens.

1️⃣ FXML: Define a Button

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.VBox?>

<VBox spacing="20" alignment="CENTER" xmlns="http://javafx.com/javafx/17"
      xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.example.MyController">

    <Button text="Click Me" fx:id="myButton" onAction="#handleButtonClick"/>
    
</VBox>

Explanation:

• fx:controller="com.example.MyController" → links this FXML to your controller class.
• fx:id="myButton" → gives the button an ID so you can access it in the controller.
• onAction="#handleButtonClick" → calls a method in the controller when the button is clicked.

2️⃣ Controller: Handle the Button

package com.example;

import javafx.fxml.FXML;
import javafx.scene.control.Button;
import javafx.scene.control.Alert;

public class MyController {

    // Link the button from FXML
    @FXML
    private Button myButton;

    // Method called when button is clicked
    @FXML
    private void handleButtonClick() {
        Alert alert = new Alert(Alert.AlertType.INFORMATION);
        alert.setTitle("Button Clicked");
        alert.setHeaderText(null);
        alert.setContentText("You clicked the button!");
        alert.showAndWait();
    }
}

Explanation:

• @FXML → allows JavaFX to inject the button from the FXML into the controller.
• handleButtonClick() → this method runs whenever the user clicks the button.
• We used an Alert to show a message, but you could do anything here (change text, open a new window, etc.).

3️⃣ Main Class: Load the FXML

package com.example;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class MainApp extends Application {

    @Override
    public void start(Stage stage) throws Exception {
        FXMLLoader loader = new FXMLLoader(getClass().getResource("my_layout.fxml"));
        Scene scene = new Scene(loader.load(), 300, 200);
        stage.setScene(scene);
        stage.setTitle("Button Example");
        stage.show();
    }

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

✅ Summary:

1. FXML defines the button and links to the controller.
2. Controller handles actions and UI logic.
3. Main class loads FXML and shows the stage.