MultiKeyCombo.java Source code

Introduction

Here is the source code for MultiKeyCombo.java

Source

/*
Definitive Guide to Swing for Java 2, Second Edition
By John Zukowski       
ISBN: 1-893115-78-X
Publisher: APress
*/

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;

import javax.swing.ComboBoxModel;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.Timer;

public class MultiKeyCombo {
    public static void main(String args[]) {
        String labels[] = { "One", "Only", "Once", "Okay", "oneself", "onlooker", "Onslaught", "Onyx", "onus",
                "onward" };
        JFrame f = new JFrame("Example JList");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JComboBox jc = new JComboBox(labels);
        MultiKeySelectionManager mk = new MultiKeySelectionManager();
        jc.setKeySelectionManager(mk);
        //    jc.setKeySelectionManager (new JComboBox.KeySelectionManager() {
        //      public int selectionForKey (char aKey, ComboBoxModel aModel) {
        //        return -1;
        //      }
        //    });
        Container c = f.getContentPane();
        c.add(jc, BorderLayout.NORTH);
        f.setSize(200, 200);
        f.setVisible(true);
    }
}

class MultiKeySelectionManager implements JComboBox.KeySelectionManager {
    private StringBuffer currentSearch = new StringBuffer();

    private Timer resetTimer;

    private final static int RESET_DELAY = 3000;

    public MultiKeySelectionManager() {
        resetTimer = new Timer(RESET_DELAY, new ActionListener() {
            public void actionPerformed(ActionEvent actionEvent) {
                currentSearch.setLength(0);
            }
        });
    }

    public int selectionForKey(char aKey, ComboBoxModel aModel) {
        // Reset if invalid character
        if (aKey == KeyEvent.CHAR_UNDEFINED) {
            currentSearch.setLength(0);
            return -1;
        }
        // Since search, don't reset search
        resetTimer.stop();
        // Convert input to uppercase
        char key = Character.toUpperCase(aKey);
        // Build up search string
        currentSearch.append(key);
        // Find selected position within model to starting searching from
        Object selectedElement = aModel.getSelectedItem();
        int selectedIndex = -1;
        if (selectedElement != null) {
            for (int i = 0, n = aModel.getSize(); i < n; i++) {
                if (aModel.getElementAt(i) == selectedElement) {
                    selectedIndex = i;
                    break;
                }
            }
        }
        boolean found = false;
        String search = currentSearch.toString();
        // Search from selected forward, wrap back to beginning if not found
        for (int i = 0, n = aModel.getSize(); i < n; i++) {
            String element = aModel.getElementAt(selectedIndex).toString().toUpperCase();
            if (element.startsWith(search)) {
                found = true;
                break;
            }
            selectedIndex++;
            if (selectedIndex == n) {
                selectedIndex = 0; // wrap
            }
        }
        // Restart timer
        resetTimer.start();
        return (found ? selectedIndex : -1);
    }
}