ListView和ComboBox示例代码

Myth丶恋晨 2022-12-07 12:12 128阅读 0赞

## 背景 **(** Background **)** ##

Below is an example of a JavaFX application that shows how to use the `ListView` and [ComboBox][] controls. Both are initially populated by an `ObservableList`. When the user selects an item in the `ListView` or an option from the `ComboBox` drop-down list, a corresponding label shows what value is selected.

下面是一个JavaFX应用程序的示例，该示例显示了如何使用`ListView`和[ComboBox][]控件。 两者最初都由`ObservableList`填充。 当用户在`ListView`选择一项或从`ComboBox`下拉列表中选择一个选项时，相应的标签将显示所选的值。

This is done by adding a `ChangeListener` to the `SelectionModel` of the `ListView` and the `ComboBox` controls.

这是通过将`ChangeListener`添加到`ListView`和`ComboBox`控件的`SelectionModel`来完成的。

## Java代码 **(** Java Code **)** ##

//List of import statements needed to reference the controls
    import javafx.application.Application;
    import javafx.beans.value.ChangeListener;
    import javafx.beans.value.ObservableValue;
    import javafx.scene.Scene;
    import javafx.scene.layout.HBox;
    import javafx.stage.Stage;
    import javafx.scene.control.Label;
    import javafx.scene.control.ComboBox;
    import javafx.scene.control.ListView;
    import javafx.collections.ObservableList;
    import javafx.collections.FXCollections;
    import javafx.scene.control.SelectionMode;
    public class JavaFXControls extends Application {
    //Main entry point into the JavaFX application
    @Override
    public void start(Stage primaryStage) {
    //Use HBOX layout panes to space out the controls
    //in a single row
    HBox comboBox = new HBox();
    HBox listBox = new HBox();
    HBox controlBox = new HBox();
    //An Observable list to populate the ListView with items
    ObservableList countries = FXCollections.observableArrayList(
    "England", "Germany", "France", "Israel", "South Africa", "U.S.A.", "Australia");
    ListView list = new ListView(countries);
    //Set the width of the ListView to be 100 pixels
    list.setPrefWidth(100);
    //Allow multiple selections from the Listview
    list.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
    //Create a naming label to highlight the selected item from the ListView
    Label listLabel = new Label("Selected List Item: ");
    //Create a label to hold the value of the selected item of the ListView
    final Label listSelection = new Label();
    listSelection.setPrefWidth(200);
    //Set up a changelistener to listen for the items being selected in the ListView
    list.getSelectionModel().selectedItemProperty().addListener(
    new ChangeListener() {
    public void changed(ObservableValue ov,
    String old_val, String new_val) {
    //Set the label with the selected item
    listSelection.setText(new_val);
    }
    });
    //Add the ListView and two labels to the HBOX layout pane
    listBox.getChildren().add(list);
    listBox.getChildren().add(listLabel);
    listBox.getChildren().add(listSelection);
    //An Observable list to populate the ComboBOx with options
    ObservableList fruits = FXCollections.observableArrayList(
    "Apple", "Banana", "Pear", "Strawberry", "Peach", "Orange", "Plum",
    "Melon", "Cherry", "Blackberry", "Melon", "Cherry", "Blackberry");
    ComboBox fruit = new ComboBox(fruits);
    //Set the dropdown list to 13 so all the options can be seen at one time
    fruit.setVisibleRowCount(13);
    //Create a naming label to highlight the selected option from the ComboBOx
    Label comboLabel = new Label("Selected Combo Item: ");
    //Create a label to hold the value of the selected option of the ComboBox
    final Label comboSelection = new Label();
    fruit.getSelectionModel().selectedItemProperty().addListener(
    new ChangeListener() {
    public void changed(ObservableValue ov,
    String old_val, String new_val) {
    //Set the label with the selected option
    comboSelection.setText(new_val);
    }
    });
    //Add the ComboBox and two labels to the HBOX layout pane
    comboBox.getChildren().add(fruit);
    comboBox.getChildren().add(comboLabel);
    comboBox.getChildren().add(comboSelection);
    //Add the two HBOXes to another HBOX to space out the controls
    controlBox.getChildren().add(listBox);
    controlBox.getChildren().add(comboBox);
    //Add the main HBOX layout pane to the scene
    Scene scene = new Scene(controlBox, 800, 250);
    //Show the form
    primaryStage.setTitle("Hello World!");
    primaryStage.setScene(scene);
    primaryStage.show();
    }
    /**
    * @param args the command line arguments
    */
    public static void main(String[] args) {
    launch(args);
    }
    }

> 翻译自: [https://www.thoughtco.com/listview-and-combobox-example-program-2033940][https_www.thoughtco.com_listview-and-combobox-example-program-2033940]

[ComboBox]: https://www.thoughtco.com/combobox-overview-2033930
[https_www.thoughtco.com_listview-and-combobox-example-program-2033940]: https://www.thoughtco.com/listview-and-combobox-example-program-2033940