Autocomplete Combobox In Java With Filtering And Inserting New Text

import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.util.ArrayList;
import java.util.List;
import javax.swing.AbstractListModel;
import javax.swing.ComboBoxModel;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.Timer;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.JTextComponent;
import javax.swing.text.PlainDocument;
import org.apache.log4j.ConsoleAppender;
import org.apache.log4j.Logger;
import org.apache.log4j.PatternLayout;

/**
 * Autocomplete combobox with filtering and
 * text inserting of new text
 * @author Exterminator13
 */
public class AutoCompleteCombo extends JComboBox{

    private static final Logger logger = Logger.getLogger(AutoCompleteCombo.class);
    private Model model = new Model();
    private final JTextComponent textComponent = (JTextComponent) getEditor().getEditorComponent();
    private boolean modelFilling = false;

    private boolean updatePopup;

    public AutoCompleteCombo() {

        setEditable(true);

        logger.debug("setPattern() called from constructor");
        setPattern(null);
        updatePopup = false;

        textComponent.setDocument(new AutoCompleteDocument());
        setModel(model);
        setSelectedItem(null);

        new Timer(20, new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                if (updatePopup && isDisplayable()) {
                    setPopupVisible(false);
                    if (model.getSize() > 0) {
                        setPopupVisible(true);
                    }
                    updatePopup = false;
                }
            }
        }).start();
    }

      private class AutoCompleteDocument extends PlainDocument {

        boolean arrowKeyPressed = false;

        public AutoCompleteDocument() {
            textComponent.addKeyListener(new KeyAdapter() {

                @Override
                public void keyPressed(KeyEvent e) {
                    int key = e.getKeyCode();
                    if (key == KeyEvent.VK_ENTER) {
                        logger.debug("[key listener] enter key pressed");
                        //there is no such element in the model for now
                        String text = textComponent.getText();
                        if (!model.data.contains(text)) {
                            logger.debug("addToTop() called from keyPressed()");
                            addToTop(text);
                        }
                    } else if (key == KeyEvent.VK_UP ||
                               key == KeyEvent.VK_DOWN) {
                        arrowKeyPressed = true;
                        logger.debug("arrow key pressed");
                    }
                }
            });
        }

        void updateModel() throws BadLocationException {
            String textToMatch = getText(0, getLength());
            logger.debug("setPattern() called from updateModel()");
            setPattern(textToMatch);
        }

        @Override
        public void remove(int offs, int len) throws BadLocationException {

            if (modelFilling) {
                logger.debug("[remove] model is being filled now");
                return;
            }

            super.remove(offs, len);
            if (arrowKeyPressed) {
                arrowKeyPressed = false;
                logger.debug("[remove] arrow key was pressed, updateModel() was NOT called");
            } else {
                logger.debug("[remove] calling updateModel()");
                updateModel();
            }
            clearSelection();
        }

        @Override
        public void insertString(int offs, String str, AttributeSet a) throws BadLocationException {

            if (modelFilling) {
                logger.debug("[insert] model is being filled now");
                return;
            }

            // insert the string into the document
            super.insertString(offs, str, a);

//            if (enterKeyPressed) {
//                logger.debug("[insertString] enter key was pressed");
//                enterKeyPressed = false;
//                return;
//            }

            String text = getText(0, getLength());
            if (arrowKeyPressed) {
                logger.debug("[insert] arrow key was pressed, updateModel() was NOT called");
                model.setSelectedItem(text);
                logger.debug( String.format("[insert] model.setSelectedItem(%s)", text) );
                arrowKeyPressed = false;
            } else if(!text.equals(getSelectedItem())){
                logger.debug("[insert] calling updateModel()");
                updateModel();
            }

            clearSelection();
        }

    }


    public void setText(String text) {
        if (model.data.contains(text)) {
            setSelectedItem(text);
        } else {
            addToTop(text);
            setSelectedIndex(0);
        }
    }

    public String getText() {
        return getEditor().getItem().toString();
    }

    private String previousPattern = null;

    private void setPattern(String pattern) {

        if(pattern!=null && pattern.trim().isEmpty())
            pattern = null;

        if(previousPattern==null && pattern ==null ||
           pattern!=null && pattern.equals(previousPattern)) {
            logger.debug("[setPatter] pattern is the same as previous: "+previousPattern);
            return;
        }

        previousPattern = pattern;

        modelFilling = true;
//        logger.debug("setPattern(): start");

        model.setPattern(pattern);

        if(logger.isDebugEnabled()) {
            StringBuilder b = new StringBuilder(100);
            b.append("pattern filter '").append(pattern==null ? "null" : pattern).append("' set:\n");
            for(int i=0; i list = new ArrayList(limit);
            private List lowercase = new ArrayList(limit);
            private List filtered;

            void add(String s) {
                list.add(s);
                lowercase.add(s.toLowerCase());
            }

            void addToTop(String s) {
                list.add(0, s);
                lowercase.add(0, s.toLowerCase());
            }

            void remove(int index) {
                list.remove(index);
                lowercase.remove(index);
            }

            List getList() {
                return list;
            }

            List getFiltered() {
                if(filtered==null)
                    filtered = list;
                return filtered;
            }

            int size() {
                return list.size();
            }

            void setPattern(String pattern) {
                if (pattern == null || pattern.isEmpty()) {
                    filtered = list;
                    AutoCompleteCombo.this.setSelectedItem(model.getElementAt(0));
                    logger.debug( String.format("[setPattern] combo.setSelectedItem(null)") );
                } else {
                    filtered = new ArrayList(limit);
                    pattern = pattern.toLowerCase();
                    for(int i=0; isize2) {
                fireIntervalRemoved(this, size2, size1-1);
                fireContentsChanged(this, 0, size2-1);
            }
        }

        public void addToTop(String aString) {
            if(aString==null || data.contains(aString))
                return;
            if(data.size()==0)
                data.add(aString);
            else
                data.addToTop(aString);

            while(data.size()>limit) {
                int index = data.size()-1;
                data.remove(index);
            }

            setPattern(null);
            model.setSelectedItem(aString);
            logger.debug( String.format("[addToTop] model.setSelectedItem(%s)", aString) );

            //saving into options
            if (data.size() > 0) {
                writeData();
            }
        }

        @Override
        public Object getSelectedItem() {
            return selected;
        }

          @Override
          public void setSelectedItem(Object anObject) {
              if ((selected != null && !selected.equals(anObject)) ||
                      selected == null && anObject != null) {
                  selected = (String) anObject;
                  fireContentsChanged(this, -1, -1);
              }
          }

        @Override
        public int getSize() {
            return data.getFiltered().size();
        }

        @Override
        public Object getElementAt(int index) {
            return data.getFiltered().get(index);
        }

    }



    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {

//                Logger root = Logger.getRootLogger();
//                root.addAppender(new ConsoleAppender(new PatternLayout("%d{ISO8601} [%5p] %m at %l%n")));
                Logger root = Logger.getRootLogger();
                root.addAppender(new ConsoleAppender(new PatternLayout("%d{ISO8601} %m at %L%n")));

//                BasicConfigurator.configure();

                JFrame frame = new JFrame();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new GridLayout(3, 1));
                final JLabel label = new JLabel("label ");
                frame.add(label);
                final AutoCompleteCombo combo = new AutoCompleteCombo();
//                combo.getEditor().getEditorComponent().addKeyListener(new KeyAdapter() {
//
//                    @Override
//                    public void keyReleased(KeyEvent e) {
//                        if (e.getKeyCode() == KeyEvent.VK_ENTER) {
//                            String text = combo.getEditor().getItem().toString();
//                            if(text.isEmpty())
//                                return;
//                            combo.addToTop(text);
//                        }
//                    }
//                });
                frame.add(combo);
                JComboBox combo2 = new JComboBox(new String[] {"Item 1", "Item 2", "Item 3", "Item 4"});
                combo2.setEditable(true);
                frame.add(combo2);
                frame.pack();
                frame.setSize( 500, frame.getHeight() );
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

}