Setting the value of custom javafx ComboBox

Question

EDIT: I have included sample files that give me errors I am trying to implement a ComboBox that filters items according to KeyStrokes, following the recipe from here. I 'd like to list countries of the world

I am having the FilterComboBox.fxml

FilterComboBox.java as in the recipe. Here is the source:

    /*
 * Follows: https://stackoverflow.com/questions/13362607/combobox-jump-to-typed-char
 */

package persondetails2.controller;

import java.net.URL;
import java.util.ResourceBundle;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.event.EventHandler;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.control.ComboBox;
import javafx.scene.control.SingleSelectionModel;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;

/**
 *
 * @author DRY
 */
public class FilterComboBox extends ComboBox {
//implements Initializable{
    private final FilterComboBox fcbo = this;

    private ObservableList items;
    private ObservableList filter;
    private String s;
    private Object selection;

    private class KeyHandler implements EventHandler {

        private SingleSelectionModel sm;

        public KeyHandler() {
            sm = getSelectionModel();
            s = "";
            System.err.println("Initialized keyhandler");
        }

        @Override
        public void handle(KeyEvent event) {
            filter.clear();
            // handle non alphanumeric keys like backspace, delete etc
            if (event.getCode() == KeyCode.BACK_SPACE && s.length() > 0) {
                s = s.substring(0, s.length() - 1);
            } else {
                s += event.getText();
            }

            if (s.length() == 0) {
                fcbo.setItems(items);
                sm.selectFirst();
                return;
            }
            //System.out.println(s);
            if (event.getCode().isLetterKey()) {
                for (T item : items) {
                    if (item.toString().toUpperCase().startsWith(s.toUpperCase())) {

                        filter.add(item);
                        System.out.println(item);

                        fcbo.setItems(filter);

                        //sm.clearSelection();
                        //sm.select(item);

                    }
                }
                sm.select(0);
            }

        }
    }

    public FilterComboBox(final ObservableList items) {
        super(items);
        this.items = items;
        this.filter = FXCollections.observableArrayList();

        setOnKeyReleased(new KeyHandler());

        this.focusedProperty().addListener(new ChangeListener() {
            @Override
            public void changed(ObservableValue observable, Object oldValue, Object newValue) {
                if ((boolean)newValue == false) {
                    s = "";
                    fcbo.setItems(items);
                    fcbo.getSelectionModel().select((T)selection);
                }

            }

        });

        this.getSelectionModel().selectedItemProperty().addListener(new ChangeListener() {
            @Override
            public void changed(ObservableValue observable, Object oldValue, Object newValue) {
                if (newValue != null) {
                    selection = (Object) newValue;
                }

            }
        });
    }

}

My main view is called PersonDetails.fxml

and the respective controller is PersonDetailsController.java

package persondetails2.controller;

import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Label;

/**
 *
 * @author DRY
 */
public class PersonDetailsController implements Initializable {

    @FXML
    private Label label;

    @FXML
    private void handleButtonAction(ActionEvent event) {
        System.out.println("You clicked me!");
        label.setText("Hello World!");
    }

    @Override
    public void initialize(URL url, ResourceBundle rb) {
        // TODO
    }    

}

This configuration gives me now an java.lang.InstantiationException: persondetails2.controller.FilterComboBox. I would like to read the data in the controller initialisation and then be able to set the values in the TextFields as well as the chosen value in the ComboBox.

Any ideas on how to continue?

Uluk Biy · Accepted Answer

Since you are setting the items for combobox in FXML file, I refactored the FilterComboBox constructor as a no-arg and added the code that loads the FXML file:

public class FilterComboBox extends ComboBox {

    private final ObservableList items;
    private final ObservableList filter;
    private String s;
    private Object selection;

    private class KeyHandler implements EventHandler {

        private SingleSelectionModel sm;

        public KeyHandler() {
            sm = getSelectionModel();
            s = "";
            System.err.println("Initialized keyhandler");
        }

        @Override
        public void handle(KeyEvent event) {
            filter.clear();
            // handle non alphanumeric keys like backspace, delete etc
            if (event.getCode() == KeyCode.BACK_SPACE && s.length() > 0) {
                s = s.substring(0, s.length() - 1);
            } else {
                s += event.getText();
            }

            if (s.length() == 0) {
                setItems(items);
                sm.selectFirst();
                return;
            }
            //System.out.println(s);
            if (event.getCode().isLetterKey()) {
                for (T item : items) {
                    if (item.toString().toUpperCase().startsWith(s.toUpperCase())) {

                        filter.add(item);
                        System.out.println(item);

                        setItems(filter);

                        //sm.clearSelection();
                        //sm.select(item);
                    }
                }
                sm.select(0);
            }

        }
    }

    public FilterComboBox() {

        FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("FilterComboBox.fxml"));
        fxmlLoader.setRoot(this);
        fxmlLoader.setController(this);
        try {
            fxmlLoader.load();
        } catch (IOException exception) {
            throw new RuntimeException(exception);
        }

        items = getItems();
        this.filter = FXCollections.observableArrayList();

        setOnKeyReleased(new KeyHandler());

        this.focusedProperty().addListener(new ChangeListener() {
            @Override
            public void changed(ObservableValue observable, Object oldValue, Object newValue) {
                if ((boolean) newValue == false) {
                    s = "";
                    setItems(items);
                    getSelectionModel().select((T) selection);
                }
            }
        });

        this.getSelectionModel().selectedItemProperty().addListener(new ChangeListener() {
            @Override
            public void changed(ObservableValue observable, Object oldValue, Object newValue) {
                if (newValue != null) {
                    selection = (Object) newValue;
                }
            }
        });
    }

}

Next, changed the FilterComboBox.fxml as:

and replaced the fx:include in PersonDetails as:

...

Setting the value of custom javafx ComboBox

Answers (1)

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