JavaFX ListView

不念不忘少年蓝@ 2023-10-14 23:09 104阅读 0赞

The JavaFX ListView control enables users to choose one or more options from a predefined list of choices. The JavaFX ListView control is represented by the class `javafx.scene.control.ListView` . This JavaFX ListView tutorial will explain how to use the `ListView` class.

### Creating a ListView ###

You create a `ListView` simply by creating a new instance of the `ListView` class. Here is a JavaFX `ListView` instantiation example:

ListView listView = new ListView();

### Adding Items to a ListView ###

You can add items (options) to a `ListView` by obtaining its item collection and add items to it. Here is an example that adds items to a JavaFX `ListView` :

listView.getItems().add("Item 1");
    listView.getItems().add("Item 2");
    listView.getItems().add("Item 3");

### Adding a ListView to the Scene Graph ###

To make a `ListView` visible you must add it to the scene graph. This means that you must add the `ListView` to a `Scene` object or to some layout component which is then attached to the `Scene` object.

Here is an example showing how to add a JavaFX `ListView` to the scene graph:

package com.jenkov.javafx.controls;
    
    import javafx.application.Application;
    import javafx.scene.Scene;
    import javafx.scene.control.ListView;
    import javafx.scene.layout.HBox;
    import javafx.stage.Stage;
    
    public class ListViewExperiments extends Application  {
    
        @Override
        public void start(Stage primaryStage) throws Exception {
            primaryStage.setTitle("ListView Experiment 1");
    
            ListView listView = new ListView();
    
            listView.getItems().add("Item 1");
            listView.getItems().add("Item 2");
            listView.getItems().add("Item 3");
    
            HBox hbox = new HBox(listView);
    
            Scene scene = new Scene(hbox, 300, 120);
            primaryStage.setScene(scene);
            primaryStage.show();
        }
    
        public static void main(String[] args) {
            Application.launch(args);
        }
    }

The application resulting from running this example would look similar to this screenshot:

![72e0e8684f6d4dd29953a3a9ff001347.png][]

Notice how the `ListView` shows multiple options by default. You can set a height and width for a `ListView`, but you cannot set explicitly how many items should be visible. The height determines that based on the height of each item displayed.

If there are more items in the `ListView` than can fit into its visiible area, the `ListView` will add scroll bars so the user can scroll up and down over the items.

### Reading the Selected Value ###

You can read the selected indexes of a `ListView` via its `SelectionModel`. Here is an example showing how to read the selected indexes of a JavaFX `ListView`:

ObservableList selectedIndices = listView.getSelectionModel().getSelectedIndices();

The `OberservableList` will contain `Integer` objects representing the indexes of the selected items in the `ListView`.

Here is a full JavaFX example with a button added which reads the selected items of the `ListView` when clicked:

package com.jenkov.javafx.controls;
    
    import javafx.application.Application;
    import javafx.collections.ObservableList;
    import javafx.scene.Scene;
    import javafx.scene.control.Button;
    import javafx.scene.control.ListView;
    import javafx.scene.control.SelectionMode;
    import javafx.scene.layout.VBox;
    import javafx.stage.Stage;
    
    public class ListViewExperiments extends Application  {
    
        @Override
        public void start(Stage primaryStage) throws Exception {
            primaryStage.setTitle("ListView Experiment 1");
    
            ListView listView = new ListView();
    
            listView.getItems().add("Item 1");
            listView.getItems().add("Item 2");
            listView.getItems().add("Item 3");
    
            Button button = new Button("Read Selected Value");
    
            button.setOnAction(event -> {
                ObservableList selectedIndices = listView.getSelectionModel().getSelectedIndices();
    
                for(Object o : selectedIndices){
                    System.out.println("o = " + o + " (" + o.getClass() + ")");
                }
            });
    
            VBox vBox = new VBox(listView, button);
    
            Scene scene = new Scene(vBox, 300, 120);
            primaryStage.setScene(scene);
            primaryStage.show();
        }
    
        public static void main(String[] args) {
            Application.launch(args);
        }
    }

### Allowing Multiple Items to be Selected ###

To allow multiple items in the `ListView` to be selected you need to set the corresponding selection mode on the `ListView` selection model. Here is an example of setting the selection mode on the JavaFX `ListView`:

listView.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);

Once you have set the `SelectionMode.MULTIPLE` on the `ListView` selection model, the user can select multiple items in the `ListView` by holding down SHIFT or CTRL when selecting additional items after the first selected item.

Here is a full JavaFX example that shows how to set a `ListView` into multiple selection mode, including a button which when clicked will write out the indices of the selected items in the `ListView` :

package com.jenkov.javafx.controls;
    
    import javafx.application.Application;
    import javafx.collections.ObservableList;
    import javafx.scene.Scene;
    import javafx.scene.control.Button;
    import javafx.scene.control.ListView;
    import javafx.scene.control.SelectionMode;
    import javafx.scene.layout.VBox;
    import javafx.stage.Stage;
    
    public class ListViewExperiments extends Application  {
    
        @Override
        public void start(Stage primaryStage) throws Exception {
            primaryStage.setTitle("ListView Experiment 1");
    
            ListView listView = new ListView();
    
            listView.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
    
            listView.getItems().add("Item 1");
            listView.getItems().add("Item 2");
            listView.getItems().add("Item 3");
    
            Button button = new Button("Read Selected Value");
    
            button.setOnAction(event -> {
                ObservableList selectedIndices = listView.getSelectionModel().getSelectedIndices();
    
                for(Object o : selectedIndices){
                    System.out.println("o = " + o + " (" + o.getClass() + ")");
                }
            });
    
            VBox vBox = new VBox(listView, button);
    
            Scene scene = new Scene(vBox, 300, 120);
            primaryStage.setScene(scene);
            primaryStage.show();
        }
    
        public static void main(String[] args) {
            Application.launch(args);
        }
    }

[72e0e8684f6d4dd29953a3a9ff001347.png]: https://img-blog.csdnimg.cn/72e0e8684f6d4dd29953a3a9ff001347.png