在ComboBox列表视图的末尾添加一个按钮

Question

我需要创建一个组合框，可以有一个按钮在其列表视图的结尾。该列表可以添加或删除项目，当项目数量超过5个时，会显示一个滚动条。此外，当选择一个项目时，该列表视图不会自动关闭。

如何像下面的截图一样添加一个按钮“新项目”？

这是源代码：

helloApplication.java

package com.example.demo;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.stage.Stage;

import java.io.IOException;

public class HelloApplication extends Application {
    @Override
    public void start(Stage stage) throws IOException {
        FXMLLoader fxmlLoader = new FXMLLoader(HelloApplication.class.getResource("hello-view.fxml"));
        Scene scene = new Scene(fxmlLoader.load(), 320, 240);
        stage.setTitle("Hello!");
        stage.setScene(scene);
        stage.show();
    }

    public static void main(String[] args) {
        launch();
    }
}

你好控制器.java

package com.example.demo;

import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.ComboBox;
import javafx.scene.control.skin.ComboBoxListViewSkin;

import java.net.URL;
import java.util.ResourceBundle;

public class HelloController implements Initializable {

    @FXML
    private ComboBox<String> frequencyPlanComboBox;

    @Override
    public void initialize(URL pURL, ResourceBundle pResourceBundle) {
        frequencyPlanComboBox.getItems()
                             .addAll("aaa", "bbb", "ccc");
        ComboBoxListViewSkin<String> comboBoxListViewSkin = new ComboBoxListViewSkin<String>(frequencyPlanComboBox);
        comboBoxListViewSkin.setHideOnClick(false);
        frequencyPlanComboBox.setSkin(comboBoxListViewSkin);
    }
}

您好，查看.fxml

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.geometry.Insets?>
<?import javafx.scene.control.ComboBox?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.layout.VBox?>

<VBox alignment="CENTER" spacing="20.0" xmlns="http://javafx.com/javafx/null" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.example.demo.HelloController">
    <padding>
        <Insets bottom="20.0" left="20.0" right="20.0" top="20.0" />
    </padding>

    <Label fx:id="welcomeText" />
   <ComboBox fx:id="frequencyPlanComboBox" prefWidth="150.0" visibleRowCount="5" />
</VBox>

Answer 1

将空值添加到组合框项列表的末尾，并使用显示该值按钮的自定义列表单元格。

import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;
import javafx.scene.control.ComboBox;
import javafx.scene.control.ListCell;
import javafx.scene.control.skin.ComboBoxListViewSkin;

import java.net.URL;
import java.util.ResourceBundle;

public class HelloController implements Initializable {

    @FXML
    private ComboBox<String> frequencyPlanComboBox;

    @Override
    public void initialize(URL pURL, ResourceBundle pResourceBundle) {
        frequencyPlanComboBox.getItems()
                .addAll("aaa", "bbb", "ccc", null);
        ComboBoxListViewSkin<String> comboBoxListViewSkin = new ComboBoxListViewSkin<String>(frequencyPlanComboBox);
        comboBoxListViewSkin.setHideOnClick(false);
        frequencyPlanComboBox.setSkin(comboBoxListViewSkin);

        frequencyPlanComboBox.setCellFactory(lv -> new ListCell<>() {
            private Button button = new Button("Add New...");
            {
                button.setOnAction(e -> {
                    /*
                    Do something
                     */
                    System.out.println("Button pressed");
                });
            }
            @Override
            protected void updateItem(String item, boolean empty) {
                super.updateItem(item, empty);
                if (empty) {
                    setText("") ;
                    setGraphic(null);
                } else if (item == null) {
                    setText("");
                    setGraphic(button);
                } else {
                    setText(item);
                    setGraphic(null);
                }
            }
        });
    }
}

您可能希望尝试设置该单元格的样式，使其看起来未被选中。