Auto comple ComboBox for JavaFX.

AutoCompleteComboBox.java

import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.event.EventHandler;
import javafx.scene.control.ComboBox;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;

import java.util.function.BiPredicate;
import java.util.stream.Collectors;

public class AutoCompleteComboBox {

    public enum AutoCompleteMode {
        STARTS_WITH((s1, s2) -> s1.toLowerCase().startsWith(s2.toLowerCase())),
        CONTAINING((s1, s2) -> s1.toLowerCase().contains(s2.toLowerCase()));

        private BiPredicate<String, String> filter;

        AutoCompleteMode(BiPredicate<String, String> filter) {
            this.filter = filter;
        }
    }

    public static <T> void autoCompleteComboBox(ComboBox<T> comboBox, AutoCompleteMode mode) {
        ObservableList<T> data = comboBox.getItems();

        comboBox.setEditable(true);
        comboBox.setOnKeyPressed(event -> comboBox.hide());
        comboBox.setOnKeyReleased(new EventHandler<KeyEvent>() {
            private boolean moveCaretToPos = false;
            private int caretPos;

            @Override
            public void handle(KeyEvent event) {
                if (event.getCode() == KeyCode.UP) {
                    caretPos = -1;
                    moveCaret(comboBox.getEditor().getText().length());
                    return;
                } else if (event.getCode() == KeyCode.DOWN) {
                    if (!comboBox.isShowing()) {
                        comboBox.show();
                    }
                    caretPos = -1;
                    moveCaret(comboBox.getEditor().getText().length());
                    return;
                } else if (event.getCode() == KeyCode.BACK_SPACE) {
                    moveCaretToPos = true;
                    caretPos = comboBox.getEditor().getCaretPosition();
                } else if (event.getCode() == KeyCode.DELETE) {
                    moveCaretToPos = true;
                    caretPos = comboBox.getEditor().getCaretPosition();
                }

                if (event.getCode() == KeyCode.RIGHT || event.getCode() == KeyCode.LEFT || event.getCode().equals(KeyCode.SHIFT) || event.getCode().equals(KeyCode.CONTROL)
                        || event.isControlDown() || event.getCode() == KeyCode.HOME
                        || event.getCode() == KeyCode.END || event.getCode() == KeyCode.TAB) {
                    return;
                }

                ObservableList<T> list = FXCollections.observableList(
                        data.stream()
                                .filter(aData -> mode.filter.test(aData.toString(), comboBox.getEditor().getText()))
                                .collect(Collectors.toList()));

                String t = comboBox.getEditor().getText();

                comboBox.setItems(list);
                comboBox.getEditor().setText(t);
                if (!moveCaretToPos) {
                    caretPos = -1;
                }
                moveCaret(t.length());
                if (!list.isEmpty()) {
                    comboBox.show();
                }
            }

            private void moveCaret(int textLength) {
                if (caretPos == -1) {
                    comboBox.getEditor().positionCaret(textLength);
                } else {
                    comboBox.getEditor().positionCaret(caretPos);
                }
                moveCaretToPos = false;
            }
        });
    }
}