问题
My question is how to generate buttons, set with car pictures, based on the checkboxes and/or radio buttons selected by a user in javafx?
I'm simulating a car dealership website with car pictures. The user should be able to filter the pictures displayed by clicking checkboxes and/or radio buttons selection.
I'm first creating all the picture buttons with a for each loop. I could use if and if/else statements to filter through the pictures but there would be duplicates. I've heard of observablelist but I haven't learned those yet.
Can someone help me out with this one please? Thank you!
ArrayList<Car> cars;
for (Car r : cars)
{
for (int i = 0; i < SIZE; i++)
{
// create buttons and set car pictures
carButton[i] = new Button();
carButton[i].setId(String.format("%d", i));
carButton[i].setGraphic(cars.get(i).getCarPicture());
}
}
回答1:
Instead of using an ArrayList for your cars, I recommend using an ObservableList:
ObservableList<Car> carsList = FXCollections.observableArrayList<>();
An ObservableList allows you to listen for changes and respond accordingly. For example, when a new Car is added to the list, you could trigger an event that automatically adds a new Button to your scene.
Here is a short demo application that shows how this would work. I did comment the code below as well and many of the concepts being used may be beyond your level, but it's one method, at least.
import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ListChangeListener;
import javafx.collections.ObservableList;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.image.ImageView;
import javafx.scene.layout.FlowPane;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
public class Main extends Application {
public static void main(String[] args) {
launch(args);
}
@Override
public void start(Stage primaryStage) {
VBox root = new VBox(5);
root.setPadding(new Insets(10));
root.setAlignment(Pos.CENTER);
// Create an ObservableList to hold our Cars
ObservableList<Car> carsList = FXCollections.observableArrayList();
// For our sample, let's use a FlowPane to display all of our buttons. We will add new buttons to this FlowPane
// automatically as new Cars are added to carsList
FlowPane flowPane = new FlowPane();
flowPane.setHgap(10);
flowPane.setVgap(5);
flowPane.setAlignment(Pos.TOP_CENTER);
// Create a ListChangeListener for our carsList. This allows us to perform some actions whenever an item is added
// to or removed from the list. For our example, we will only do something when a new Car is added.
carsList.addListener(new ListChangeListener<Car>() {
@Override
public void onChanged(Change<? extends Car> c) {
System.out.println(carsList.size());
// Get the first change
c.next();
// If an item was added to the list...
if (c.wasAdded()) {
// Create a new button and add it to the FlowPane
// The Change (c) provides access to a List of items that were added during this change. Since we
// are only going to add one Car at a time, we only need to get the first item from the AddedSubList
Button button = new Button(c.getAddedSubList().get(0).getName());
button.setGraphic(c.getAddedSubList().get(0).getIcon());
button.setOnAction(event -> {
// The code to be executed when this button is clicked goes here
});
// Add the button to our FlowPane
flowPane.getChildren().add(button);
}
}
});
// Now we need a Button that will add a new car to the List
Button button = new Button("Add Car");
button.setOnAction(event -> {
// We'll just add a random car to the carsList
carsList.add(new Car("Car #" + (carsList.size() + 1), new ImageView("icon.png")));
});
// Add our FlowPane and Button to the root layout
root.getChildren().addAll(button, flowPane);
primaryStage.setScene(new Scene(root, 550, 250));
primaryStage.show();
}
}
class Car {
private final String name;
private final ImageView icon;
public Car(String name, ImageView icon) {
this.name = name;
this.icon = icon;
}
public String getName() {
return name;
}
public ImageView getIcon() {
return icon;
}
}
The Results: (after clicking the "Add Car" button a few times)
回答2:
This is a terrible implementation but It will give you some ideas on how to do things. You need to research FilteredList, ListView, and Predicate. This implementation does not handle more than one CheckBox at a time. It will only display the last CheckBox action.
CarList
import java.util.ArrayList;
import java.util.List;
import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.collections.transformation.FilteredList;
import javafx.scene.Scene;
import javafx.scene.control.CheckBox;
import javafx.scene.control.ListCell;
import javafx.scene.control.ListView;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Priority;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
/**
*
* @author Sedrick
*/
public class CarList extends Application {
@Override
public void start(Stage primaryStage) {
List<Car> cars = new ArrayList();
cars.add(new Car("Honda", "2004"));
cars.add(new Car("Ford", "2005"));
cars.add(new Car("Ford", "2004"));
cars.add(new Car("Honda", "2005"));
cars.add(new Car("Toyota", "2004"));
cars.add(new Car("Cadillac", "2005"));
ListView<Car> view = new ListView();
view.setCellFactory((ListView<Car> param) -> {
ListCell<Car> cell = new ListCell<Car>() {
CarView carView = new CarView();
@Override
protected void updateItem(Car item, boolean empty) {
super.updateItem(item, empty);
if (item != null) {
setText("");
carView.setMake(item.getMake());
carView.setModel(item.getModel());
carView.setImageView(item.getUrl());
setGraphic(carView);
} else {
setText("");
setGraphic(null);
}
}
};
return cell;
});
ObservableList<Car> data = FXCollections.observableArrayList(cars);
FilteredList<Car> filteredList = new FilteredList(data);
view.setItems(filteredList);
HBox.setHgrow(view, Priority.ALWAYS);
CheckBox checkBox = new CheckBox("Honda");
checkBox.selectedProperty().addListener((observable, oldValue, newValue) -> {
if(newValue)
{
filteredList.setPredicate((item) -> {
return item.getMake().equals("Honda");
});
}
else{
filteredList.setPredicate((item) -> {
return true;
});
}
});
CheckBox checkBox2 = new CheckBox("Ford");
checkBox2.selectedProperty().addListener((observable, oldValue, newValue) -> {
if(newValue)
{
filteredList.setPredicate((item) -> {
return item.getMake().equals("Ford");
});
}
else{
filteredList.setPredicate((item) -> {
return true;
});
}
});
CheckBox checkBox3 = new CheckBox("2004");
checkBox3.selectedProperty().addListener((observable, oldValue, newValue) -> {
if(newValue)
{
filteredList.setPredicate((item) -> {
return item.getModel().equals("2004");
});
}
else{
filteredList.setPredicate((item) -> {
return true;
});
}
});
CheckBox checkBox4 = new CheckBox("2005");
checkBox4.selectedProperty().addListener((observable, oldValue, newValue) -> {
if(newValue)
{
filteredList.setPredicate((item) -> {
return item.getModel().equals("2005");
});
}
else{
filteredList.setPredicate((item) -> {
return true;
});
}
});
VBox leftPanel = new VBox(checkBox, checkBox2, checkBox3, checkBox4);
HBox root = new HBox(leftPanel, view);
Scene scene = new Scene(root, 625, 500);
primaryStage.setTitle("Hello World!");
primaryStage.setScene(scene);
primaryStage.show();
}
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
launch(args);
}
}
CarView
import javafx.scene.control.Label;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Priority;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
/**
*
* @author Sedrick
*/
final public class CarView extends HBox{
Label make = new Label();
Label model = new Label();
ImageView imageView = new ImageView();
public CarView(String make, String model, String url) {
this.make.setText(make);
this.model.setText(model);
HBox row1 = new HBox(new Label("Make: "), this.make);
HBox row2 = new HBox(new Label("Model: "), this.model);
VBox vbox = new VBox(row1, row2);
vbox.setMaxSize(USE_PREF_SIZE, USE_PREF_SIZE);
StackPane stackPane1 = new StackPane(vbox);
HBox.setHgrow(stackPane1, Priority.ALWAYS);
Image image = new Image(url);
this.imageView.setImage(image);
this.imageView.setFitHeight(100);
this.imageView.setFitWidth(200);
StackPane stackPane2 = new StackPane(this.imageView);
stackPane2.setStyle("-fx-background-color: yellow");
getChildren().addAll(stackPane1, stackPane2);
setPrefSize(500, 125);
}
public CarView()
{
HBox row1 = new HBox(new Label("Make: "), this.make);
HBox row2 = new HBox(new Label("Model: "), this.model);
VBox vbox = new VBox(row1, row2);
vbox.setMaxSize(USE_PREF_SIZE, USE_PREF_SIZE);
StackPane stackPane1 = new StackPane(vbox);
HBox.setHgrow(stackPane1, Priority.ALWAYS);
this.imageView.setFitHeight(100);
this.imageView.setFitWidth(200);
StackPane stackPane2 = new StackPane(this.imageView);
stackPane2.setStyle("-fx-background-color: yellow");
getChildren().addAll(stackPane1, stackPane2);
setPrefSize(500, 125);
}
public void setImageView(String url) {
Image image = new Image(url);
this.imageView.setImage(image);
}
public void setMake(String make) {
this.make.setText(make);
}
public void setModel(String model)
{
this.model.setText(model);
}
}
Car
/**
*
* @author Sedrick
*/
public class Car {
private String make;
private String model;
private String url = "https://cdn.pixabay.com/photo/2012/05/29/00/43/car-49278_960_720.jpg";
public Car(String make, String model) {
this.make = make;
this.model = model;
}
public String getMake() {
return make;
}
public String getModel() {
return model;
}
public String getUrl()
{
return url;
}
public void setMake(String make) {
this.make = make;
}
public void setModel(String model) {
this.model = model;
}
}
来源：https://stackoverflow.com/questions/53401366/how-to-generate-buttonpicture-based-on-checkboxes-selection-in-javafx