Question

Write a program that simulates four cars racing. You can set the speed for each car, with maximum 100.

Java language

Answer 1

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.stage.Stage;
import javafx.scene.layout.HBox;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.VBox;
import javafx.scene.control.Label;
import javafx.geometry.Pos;
import javafx.scene.control.TextField;
import javafx.scene.Node;
import javafx.collections.ObservableList;
import javafx.scene.input.KeyCode;

public class Exercise_16_25 extends Application {
protected HBox paneForSpeed = new HBox(5);
protected VBox paneForCars = new VBox(5);
protected ObservableList<Node> textFields = paneForSpeed.getChildren();
protected ObservableList<Node> cars = paneForCars.getChildren();

@Override // Override the start method in the Application class
public void start(Stage primaryStage) {
final int NUMBER_OF_CARS = 4;
final int PREF_COLUMN_COUNT = 2;

paneForSpeed.setAlignment(Pos.CENTER);

// keep the labels and text field in a pane
for (int i = 0; i < NUMBER_OF_CARS; i++) {
paneForSpeed.getChildren().addAll(
new Label("Car " + (i + 1) + ":"), new TextField());
}

// Set specified properties for each text field in a list
for (int i = 1; i < textFields.size(); i+= 2) {
((TextField)textFields.get(i)).setPrefColumnCount(PREF_COLUMN_COUNT);
}

// Place nodes in a pane for cars
for (int i = 0; i < NUMBER_OF_CARS; i++) {
paneForCars.getChildren().add(new CarPane());
}

// Set specified properties for each element in a list
for (Node car: cars) {
((CarPane)car).setStyle("-fx-border-color: black");
((CarPane)car).setY(40);
}

// Create and register handlers
for (int i = 1; i < textFields.size(); i += 2) {
((TextField)textFields.get(i)).setOnKeyPressed(e -> {
if (e.getCode() == KeyCode.ENTER) {
setSpeed();
}
});

}

// Create a border pane
BorderPane pane = new BorderPane();
pane.setTop(paneForSpeed);
pane.setCenter(paneForCars);

// Create a scene and place it in the stage
Scene scene = new Scene(pane, 400, 200);
primaryStage.setTitle("Exercise_16_25"); // Set the stage title
primaryStage.setScene(scene); // Place the scene in the stage
primaryStage.show(); // Display the stage
}

/** Set specified rate for a CarPane list */
private void setSpeed() {
for (int i = 1, j = 0; i < textFields.size(); i += 2, j++) {
if (((TextField)textFields.get(i)).getText().length() > 0) {
((CarPane)cars.get(j)).setSpeed(
Double.parseDouble(((TextField)textFields.get(i)).getText()));
((CarPane)cars.get(j)).play();
}
else {
((CarPane)cars.get(j)).pause();
}
}
}
}