Question

This is in Java: A JavaFX application that creates polyline shapes dynamically using mouse clicks. Each mouse click adds a new line segment to the current polyline from the previous point to the current mouse position. Allow the user to end the current polyline with a double click. Also provide a button that clears the window and allows the user to begin again. Please no Jpanel thank you!

Answer 1

Here is the completed code for this problem. Comments are included, go through it, learn how things work and let me know if you have any doubts or if you need anything to change. If you are satisfied with the solution, please rate the answer. If not, PLEASE let me know before you rate, I’ll help you fix whatever issues. Thanks

Notes: The first line will be visible only after second click. On first click, the starting coordinate will be recorded, on the second click, line from first point to second will be drawn. Also in case of double clicks, the final line will be drawn before moving to the next polyline.

//DrawPolylines.java

import javafx.application.Application;
import static javafx.application.Application.launch;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.Pane;
import javafx.scene.shape.Polyline;
import javafx.stage.Stage;

public class DrawPolylines extends Application {

    Polyline current; //current Polyline being drawn

    @Override
    public void start(Stage primaryStage) {

        //creating a BorderPane
        BorderPane root = new BorderPane();
        root.setPadding(new Insets(10));

        //initializing current to null
        current = null;
        //creating a Pane to hold polylines
        Pane pane = new Pane();

        //creating clear button
        Button clr = new Button("Clear");

        //adding event listener
        clr.setOnAction(e -> {
            //clearing pane contents and setting current to null
            pane.getChildren().clear();
            current = null;
        });

        //event listener for mouse click on pane
        pane.setOnMouseClicked(e -> {
            //checking number of clicks (single or double)
            if (e.getClickCount() == 1) {
                //if current is null, initializing current with current mouse coordinates
                if (current == null) {
                    current = new Polyline(e.getX(), e.getY());
                    //and adding to pane
                    pane.getChildren().add(current);
                } else {
                    //otherwise adding current coordinates to current polyline
                    current.getPoints().addAll(e.getX(), e.getY());
                    //as current is already on pane, we dont need to add again
                }
            } else {
                //double click, in which case we set current to null, so next click will start a 
                //new polyline, and leave the existing line on the screen.
                current = null;
            }

        });

        //adding pane to center and clr to bottom
        root.setCenter(pane);
        root.setBottom(clr);

        //setting up and displaying a scene
        Scene scene = new Scene(root, 500, 500);
        primaryStage.setScene(scene);
        primaryStage.setTitle("Polylines");
        primaryStage.show();
    }

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

}

/*OUTPUT*/

- Polylines х JAVA Clear