A Simple Hex Color Analyzer in JavaFX

I was explaining Regular Expressions to one of my friend and suddenly he ask,
Can we extract hex colors from a CSS file using Regex?
And here I just throw this code using the same idea.

Basically the idea is pretty simple, we fetch some css file or html containing hex colors, Grab those colors and turn them into colorful Rectangles using JavaFX.

You can provide any page url that contains hex colors, For example https://www.google.com will work fine,
But its recommended to use css urls such as this , this, or this or any you want.

Clicking on the Rectangle will show the #hex value at bottom of the app, And just a side note, The below code is written in Java 8 so it "may" look alien to some of you, if yes, feel free to comment and ask what you do not understand or you can mention me on twitter @hacktw

By the way the Regex that i use is this → "#([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})", of course this can be simplified but i like it that way , Simplify it on your own and feel free to share the simplified version in comments.

import java.net.URL;
import java.util.Set;
import java.util.HashSet;
import javafx.scene.Scene;
import javafx.stage.Stage;
import java.io.IOException;
import java.io.BufferedReader;
import java.net.URLConnection;
import javafx.geometry.Insets;
import javafx.concurrent.Task;
import javafx.scene.text.Font;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javafx.event.ActionEvent;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
import java.io.InputStreamReader;
import javafx.concurrent.Service;
import javafx.scene.control.Alert;
import javafx.application.Platform;
import javafx.scene.control.Button;
import javafx.scene.layout.Priority;
import javafx.scene.layout.TilePane;
import javafx.scene.shape.Rectangle;
import javafx.application.Application;
import javafx.scene.control.TextField;
import javafx.scene.effect.DropShadow;
import javafx.scene.control.ScrollPane;
import javafx.scene.control.Alert.AlertType;

/**
 *
 * @author Aamir khan
 */
public class HexAnalyzer extends Application {

    final String HEX_PATTERN_STRING = "#([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})";
    final String CSS_URL = "https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css";
    Pattern pattern;
    TilePane colorsPane;
    TextField urlField;
    TextField colorVal;
    Button fetchBtn;

    @Override
    public void init() {
        pattern = Pattern.compile(HEX_PATTERN_STRING);
        urlField = new TextField(CSS_URL);
        fetchBtn = new Button("Fetch");
        fetchBtn.setPrefWidth(80.0);
        fetchBtn.setDefaultButton(true);
        colorVal = new TextField();
        colorVal.setVisible(false);
        colorsPane = new TilePane();

    }

    @Override
    public void start(Stage window) {

        colorVal.setFont(Font.font(14.0));

        HBox bar = new HBox(urlField, fetchBtn);
        bar.setSpacing(1.5);
        bar.setPadding(new Insets(5));
        HBox.setHgrow(urlField, Priority.ALWAYS);

        ScrollPane colorPane = new ScrollPane(colorsPane);
        colorPane.setFitToWidth(true);

        VBox root = new VBox(bar, colorPane, colorVal);

        window.setTitle("#HEX Color Analyzer");
        window.setScene(new Scene(root, 610, 400));
        window.show();

        fetchBtn.setOnAction(this::runTask);
    }

    boolean wasTaskStarted = false;

    private void runTask(ActionEvent e) {
        colorsPane.getChildren().clear();
        Service task = prepareTask();
        bindProperties(task);

        if (wasTaskStarted) {
            task.restart();
        } else {
            task.start();
            wasTaskStarted = true;
        }

    }

    private Service prepareTask() {
        return new Service() {
            @Override
            protected Task createTask() {
                return new Task() {
                    @Override
                    protected Void call() throws Exception {

                        try {

                            final String css = fetchDataFrom(urlField.getText());
                            final Set hexColors = extractHexColors(css);

                            hexColors.forEach(color -> {
                                Rectangle colorBox = new Rectangle(40, 40, Color.web(color));
                                colorBox.setEffect(new DropShadow(3, Color.rgb(0, 0, 0, 0.5)));
                                colorBox.setUserData(color);

                                colorBox.setOnMouseClicked(ae -> {
                                    final String val = colorBox.getUserData().toString().toUpperCase();
                                    colorVal.setText(val);
                                });
                                Platform.runLater(() -> {
                                    colorsPane.getChildren().add(colorBox);
                                });
                            });
                        } catch (IOException ex) {
                            Alert alert = new Alert(AlertType.ERROR);
                            alert.setTitle("Error");
                            alert.setHeaderText("Oops, Something went wrong");
                            alert.setContentText(ex.toString());
                            alert.showAndWait();
                        }
                        return null;
                    }

                    //Util method to fetch data from the given url
                    private String fetchDataFrom(String url) throws IOException {
                        updateMessage("Fetching");
                        StringBuilder result = new StringBuilder();
                        URL cssurl = new URL(url);
                        URLConnection data = cssurl.openConnection();
                        try (BufferedReader in = new BufferedReader(
                                new InputStreamReader(
                                        data.getInputStream())
                        )) {
                            in.lines().forEach(result::append);
                        }
                        updateMessage("Done");

                        return result.toString();

                    }

                    //Util method to extract hex colors from the given String
                    private Set extractHexColors(final String css) {
                        updateMessage("extracting hex");
                        Set colorSet = new HashSet();
                        Matcher matcher = pattern.matcher(css);
                        while (matcher.find()) {
                            colorSet.add(matcher.group(0));
                        }
                        return colorSet;
                    }

                    @Override
                    public void succeeded() {
                        super.succeeded();
                        updateMessage("Fetch");//restrore the button
                        colorVal.setText("");//remove any previous val
                    }
                };
            }

        };
    }

    private void bindProperties(Service task) {
        fetchBtn.textProperty().bind(task.messageProperty());
        fetchBtn.disableProperty().bind(task.runningProperty());
        colorVal.visibleProperty().bind(task.runningProperty().not());
    }

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

Download Project

Please note that this code may have some flaws, I have not given much time to this code its just for fun. Feel free to point out any flaw if you find out...