How to make scene local JavaFX - javafx

Question

The scene at the start of lambda has an error that is not local. How to make it local. I tried adding up top but shows null. How to make scene local at the lambda because scene sets primaryStage. I need the other nodes for GridPane. I am trying to draw on the canvas. Please help fix this problem. Thank you in advanced!
import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.control.Button;
import javafx.scene.control.RadioButton;
import javafx.scene.control.TextField;
import javafx.scene.control.ToggleGroup;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
public class TestFX extends Application {
Node scene; // i tried adding this but throws null at the lambda
#Override
public void start(Stage primaryStage) throws Exception {
primaryStage.setTitle("MyPaint");
RadioButton radioButton1 = new RadioButton("Draw");
RadioButton radioButton2 = new RadioButton("Erase");
RadioButton radioButton3 = new RadioButton("Circle");
ToggleGroup radioGroup = new ToggleGroup();
radioButton1.setToggleGroup(radioGroup);
radioButton2.setToggleGroup(radioGroup);
radioButton3.setToggleGroup(radioGroup);
Button b1 = new Button("Clear Canvas");
TextField colorText = new TextField();
colorText.setText("Colors");
Canvas canvas = new Canvas(300, 250);
GraphicsContext gc = canvas.getGraphicsContext2D();
// scene cannot be resolved without initializing at top: Node scene;
scene.setOnMousePressed(q -> {
gc.setFill(Color.BLACK);
gc.setLineWidth(1);
gc.beginPath();
gc.lineTo(q.getSceneX(),
q.getSceneY());
gc.getStroke();
});
gc.strokeText("Hello Canvas", 150, 100);
GridPane gridPane = new GridPane();
GridPane.setConstraints(radioButton1, 0, 0);
GridPane.setConstraints(radioButton2, 0, 1);
GridPane.setConstraints(radioButton3, 0, 2);
GridPane.setConstraints(colorText, 0, 3);
GridPane.setConstraints(b1, 0, 4);
GridPane.setConstraints(canvas, 1, 1);
// adding spaces between radiobutton, button and radiobutton
radioButton1.setPadding(new Insets(15));
radioButton2.setPadding(new Insets(15));
radioButton3.setPadding(new Insets(15));
b1.setPadding(new Insets(15));
colorText.setPadding(new Insets(15));
gridPane.getChildren().addAll(radioButton1, radioButton2, radioButton3, colorText, b1, canvas);
Scene scene = new Scene(gridPane, 800, 800);
primaryStage.setScene(scene);
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}

Answer 1

You define Scene in this part of the code:
gridPane.getChildren().addAll(radioButton1, radioButton2, radioButton3, colorText, b1, canvas);
Scene scene = new Scene(gridPane, 800, 800);
primaryStage.setScene(scene);
primaryStage.show()
but you are calling this code before you define Scene.
// scene cannot be resolved without initializing at top: Node scene;
scene.setOnMousePressed(q -> {
gc.setFill(Color.BLACK);
gc.setLineWidth(1);
gc.beginPath();
gc.lineTo(q.getSceneX(),
q.getSceneY());
gc.getStroke();
});
You need to delete Node scene. and move the scene.setOnMousePressed() code to a place after where you defined the Scene.
Full Code:
import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.control.Button;
import javafx.scene.control.RadioButton;
import javafx.scene.control.TextField;
import javafx.scene.control.ToggleGroup;
import javafx.scene.layout.GridPane;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
public class TestFX extends Application {
#Override
public void start(Stage primaryStage) throws Exception {
primaryStage.setTitle("MyPaint");
RadioButton radioButton1 = new RadioButton("Draw");
RadioButton radioButton2 = new RadioButton("Erase");
RadioButton radioButton3 = new RadioButton("Circle");
ToggleGroup radioGroup = new ToggleGroup();
radioButton1.setToggleGroup(radioGroup);
radioButton2.setToggleGroup(radioGroup);
radioButton3.setToggleGroup(radioGroup);
Button b1 = new Button("Clear Canvas");
TextField colorText = new TextField();
colorText.setText("Colors");
Canvas canvas = new Canvas(300, 250);
GraphicsContext gc = canvas.getGraphicsContext2D();
gc.strokeText("Hello Canvas", 150, 100);
GridPane gridPane = new GridPane();
GridPane.setConstraints(radioButton1, 0, 0);
GridPane.setConstraints(radioButton2, 0, 1);
GridPane.setConstraints(radioButton3, 0, 2);
GridPane.setConstraints(colorText, 0, 3);
GridPane.setConstraints(b1, 0, 4);
GridPane.setConstraints(canvas, 1, 1);
// adding spaces between radiobutton, button and radiobutton
radioButton1.setPadding(new Insets(15));
radioButton2.setPadding(new Insets(15));
radioButton3.setPadding(new Insets(15));
b1.setPadding(new Insets(15));
colorText.setPadding(new Insets(15));
gridPane.getChildren().addAll(radioButton1, radioButton2, radioButton3, colorText, b1, canvas);
Scene scene = new Scene(gridPane, 800, 800);
scene.setOnMousePressed(q -> {
gc.setFill(Color.BLACK);
gc.setLineWidth(1);
gc.beginPath();
gc.lineTo(q.getSceneX(),
q.getSceneY());
gc.getStroke();
});
primaryStage.setScene(scene);
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}