import java.awt.EventQueue;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
import javax.swing.DefaultComboBoxModel;
import javax.swing.JComboBox;
import javax.swing.JTextField;
 
public class AutoSuggest<E> extends JComboBox<E> {
 
    private final JComboBox<E> comboBox = this;
    private final JTextField textField = (JTextField) getEditor().getEditorComponent();
    private final List<String> suggestions = new LinkedList<>();
    private boolean hide_flag = false;
 
    public AutoSuggest() {
        super();
 
        setEditable(true);
 
        textField.addKeyListener(new KeyAdapter() {
            @Override
            public void keyTyped(KeyEvent e) {
                EventQueue.invokeLater(() -> {
                    String text = textField.getText();
                    if (text.length() == 0) {
                        comboBox.hidePopup();
                        setModel(new DefaultComboBoxModel(suggestions.toArray()), "");
                    } else {
                        DefaultComboBoxModel m = getSuggestedModel(suggestions, text);
                        if (m.getSize() == 0 || hide_flag) {
                            comboBox.hidePopup();
                            hide_flag = false;
                        } else {
                            setModel(m, text);
                            comboBox.showPopup();
                        }
                    }
                });
            }
 
            @Override
            public void keyPressed(KeyEvent e) {
                String text = textField.getText();
                int code = e.getKeyCode();
                switch (code) {
                    case KeyEvent.VK_ENTER:
                        if (!suggestions.contains(text)) {
                            suggestions.add(text);
                            Collections.sort(suggestions);
                            setModel(getSuggestedModel(suggestions, text), text);
                        }
                        hide_flag = true;
                        break;
                    case KeyEvent.VK_ESCAPE:
                        hide_flag = true;
                        break;
                    case KeyEvent.VK_RIGHT:
                        for (int i = 0; i < suggestions.size(); i++) {
                            String str = suggestions.get(i);
                            if (str.startsWith(text)) {
                                comboBox.setSelectedIndex(-1);
                                textField.setText(str);
                                return;
                            }
                        }
                        break;
                    default:
                        break;
                }
            }
        });
 
        setModel(new DefaultComboBoxModel(suggestions.toArray()), "");
    }
 
    public void update(Set<String> terms) {
        textField.setText("");
 
        suggestions.clear();
        suggestions.addAll(terms);
 
        setModel(new DefaultComboBoxModel(suggestions.toArray()), "");
    }
 
    private void setModel(DefaultComboBoxModel defaultComboBoxModel, String text) {
        comboBox.setModel(defaultComboBoxModel);
        comboBox.setSelectedIndex(-1);
        textField.setText(text);
    }
 
    private static DefaultComboBoxModel getSuggestedModel(List<String> list, String text) {
        DefaultComboBoxModel m = new DefaultComboBoxModel();
        list.stream().filter((s) -> (s.toLowerCase().startsWith(text.toLowerCase()))).forEach((s) -> {
            m.addElement(s);
        });
        return m;
    }
 
    public JTextField getTextField() {
        return textField;
    }
 
    public String getText() {
        return textField.getText();
    }
 
}

import java.awt.Color;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Insets;
import java.awt.RenderingHints;
import javax.swing.JTextField;
 
public class JHintTextField extends JTextField {
 
    private String hint = "";
 
    public JHintTextField() {
    }
 
    public JHintTextField(String hint) {
        setHint(hint);
    }
 
    public final void setHint(String hint) {
        if (hint != null) {
            this.hint = hint;
        } else {
            this.hint = "";
        }
    }
 
    @Override
    public void paint(Graphics g) {
        super.paint(g);
        if (getText().length() == 0) {
            int h = getHeight();
            ((Graphics2D) g).setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
            Insets ins = getInsets();
            FontMetrics fm = g.getFontMetrics();
            int c0 = getBackground().getRGB();
            int c1 = getForeground().getRGB();
            int m = 0xfefefefe;
            int c2 = ((c0 & m) >>> 1) + ((c1 & m) >>> 1);
            g.setColor(new Color(c2, true));
            g.drawString(hint, ins.left, h / 2 + fm.getAscent() / 2 - 1);
        }
    }
}

import java.awt.Color;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import javax.swing.UIManager;
 
public class FocusHighlighter implements FocusListener {
 
    @Override
    public void focusGained(FocusEvent e) {
        e.getComponent().setBackground(Color.YELLOW);
    }
 
    @Override
    public void focusLost(FocusEvent e) {
        e.getComponent().setBackground(UIManager.getColor("TextField.background"));
    }
}

import java.awt.event.KeyEvent;
import javax.swing.JComponent;
import javax.swing.JDialog;
import javax.swing.KeyStroke;
 
public class DisposeWithESC {
 
    private DisposeWithESC() {
    }
 
    public static void attach(JDialog jDialog) {
        jDialog.getRootPane().registerKeyboardAction(e -> {
            jDialog.dispose();
        }, KeyStroke.getKeyStroke(KeyEvent.VK_ESCAPE, 0), JComponent.WHEN_IN_FOCUSED_WINDOW);
    }
 
}