load a class

[Sammer Meer]

I have a program with a combo box, when i choose an item from the combo my program must go to a certain class and invoke a method in it , how can i do that?..how can i invoke this method in that certain class?

[Ali Gohar]

Not got the problem. please explain briefly. what type of application you are creating? is it web applicatoin with jsp or servlet? what type of method you want to call.
You can call any method just by creating the object of that class.

[Sammer Meer]

No, it's an application that deals with Barcodes.. I have to make for each standard a jar file that contains the classes necessary for encoding/decoding related to that standrd.An obligatory class (that must exist in every valid jar file) is a class derived JPanel.. I want to load this class from a certain jar file when the user chooses a standard (that's related to that jar file) from a ComboBox, and then I want to make an instance of that class (which extends JPanel) and add this panel to my frame..

[Kush Kush]

USE
Class.forName(path to your class)
It will load ur class.
Note Class is a Class itself and forName is static method.

[Dirk Schreckmann]

Sammer,
I'm guessing a little that what you're trying to figure out is mostly GUI-related - eg. handling events, displaying panels.
As such, I'm moving this to the Swing / JFC / AWT forum...

[somkiat puisungnoen]

you must have main class for control UI and UI module class is base class for create UI in each panel

  
package com.account.ui;
import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.GraphicsEnvironment;
import java.awt.Insets;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ContainerEvent;
import java.awt.event.ContainerListener;
import java.lang.reflect.Constructor;
import java.util.Vector;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.ButtonGroup;
import javax.swing.Icon;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.JToggleButton;
import javax.swing.JToolBar;
import javax.swing.SwingUtilities;
import javax.swing.border.EtchedBorder;
public class MainUI extends JPanel {
private JFrame frame;
private JMenuBar menuBar;
private JPanel programPanel;
private JTextField statusField;
private JButton basicButton, advanceButton;
private ToggleButtonToolBar toolbar;
private ButtonGroup toolbarGroup = new ButtonGroup();
private UIModule currentModule;
private Vector screensVector = new Vector();
private static int numSSs = 0;
private Vector mainUIs = new Vector();
String[] screen =
{
"com.account.ui.BasicSearch",
"com.account.ui.AdvanceSearch",
"com.account.ui.ManageData" };
public MainUI() {
frame = createFrame();
setLayout(new BorderLayout());
setPreferredSize(new Dimension(720, 640));
initial();
preload();
SwingUtilities.invokeLater(new Runnable() {
public void run() {
showMain();
}
});
//Start loading the rest of the demo in the background
DemoLoadThread demoLoader = new DemoLoadThread(this);
demoLoader.start();
}
void loadScreens() {
for (int i = 0; i < screen.length; i++) {
loadScreen(screen[i]);
}
}
void loadScreen(String classname) {
setStatus(classname);
UIModule demo = null;
try {
Class demoClass = Class.forName(classname);
Constructor demoConstructor =
demoClass.getConstructor(
new Class[] { com.account.ui.MainUI.class });
demo =
(UIModule) demoConstructor.newInstance(new Object[] { this });
addUI(demo);
} catch (Exception e) {
e.printStackTrace();
System.out.println("Error occurred loading demo: " + classname + e);
}
}
public void showMain() {
JFrame frame = getFrame();
frame.setTitle("Account Program");
frame.getContentPane().add(this, BorderLayout.CENTER);
frame.pack();
frame.show();
numSSs++;
mainUIs.add(this);
}
public void initial() {
JPanel top = new JPanel();
top.setLayout(new BorderLayout());
add(top, BorderLayout.NORTH);
menuBar = createMenus();
top.add(menuBar, BorderLayout.NORTH);
ToolBarPanel toolbarPanel = new ToolBarPanel();
toolbarPanel.setLayout(new BorderLayout());
toolbar = new ToggleButtonToolBar();
toolbarPanel.add(toolbar, BorderLayout.CENTER);
top.add(toolbarPanel, BorderLayout.SOUTH);
toolbarPanel.addContainerListener(toolbarPanel);
statusField = new JTextField("Status bar");
statusField.setEditable(false);
add(statusField, BorderLayout.SOUTH);
programPanel = new JPanel();
programPanel.setLayout(new BorderLayout());
programPanel.setBorder(new EtchedBorder());
add(programPanel, BorderLayout.CENTER);
}
public void preload() {
UIModule mo = new BasicSearch(this);
setUI(mo);
}
public UIModule addUI(UIModule uiModule) {
screensVector.addElement(uiModule);
// do the following on the gui thread
SwingUtilities.invokeLater(new SwingSetRunnable(this, uiModule) {
public void run() {
SwitchToDemoAction action =
new SwitchToDemoAction(mainUI, (UIModule) obj);
JToggleButton tb = mainUI.getToolBar().addToggleButton(action);
mainUI.getToolBarGroup().add(tb);
tb.setText(null);
//tb.setText(((UIModule) obj).getName());
if (mainUI.getToolBarGroup().getSelection() == null) {
tb.setSelected(true);
}
//tb.setToolTipText(((UIModule) obj).getToolTip());
if (screen[screen.length
- 1].equals(obj.getClass().getName())) {
setStatus("");
}
}
});
return uiModule;
}
public void setUI(UIModule currentModule) {
this.currentModule = currentModule;
JComponent currentPanel = currentModule.getPanel();
SwingUtilities.updateComponentTreeUI(currentPanel);
programPanel.setVisible(false);
programPanel.removeAll();
programPanel.add(currentPanel, BorderLayout.CENTER);
programPanel.setVisible(true);
}
public JMenuBar createMenus() {
JMenuItem mi;
JMenuBar meuBar = new JMenuBar();
JMenu fileMenu = (JMenu) meuBar.add(new JMenu("File"));
createMenuItem(fileMenu, "Test1");
createMenuItem(fileMenu, "Test2");
return meuBar;
}
public JMenuItem createMenuItem(JMenu menu, String label) {
JMenuItem mi = (JMenuItem) menu.add(new JMenuItem(label));
return mi;
}
public JFrame createFrame() {
JFrame frame =
new JFrame(
GraphicsEnvironment
.getLocalGraphicsEnvironment()
.getDefaultScreenDevice()
.getDefaultConfiguration());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
return frame;
}
public ToggleButtonToolBar getToolBar() {
return toolbar;
}
public ButtonGroup getToolBarGroup() {
return toolbarGroup;
}
public JFrame getFrame() {
return frame;
}
public void setStatus(String msg) {
SwingUtilities.invokeLater(new SwingSetRunnable(this, msg) {
public void run() {
mainUI.statusField.setText((String) obj);
}
});
}
public static void main(String[] args) {
new MainUI();
}
class DemoLoadThread extends Thread {
MainUI mainUI;
public DemoLoadThread(MainUI mainUI) {
this.mainUI = mainUI;
}
public void run() {
mainUI.loadScreens();
}
}
class SwingSetRunnable implements Runnable {
protected MainUI mainUI;
protected Object obj;
public SwingSetRunnable(MainUI mainUI, Object obj) {
this.mainUI = mainUI;
this.obj = obj;
}
public void run() {
}
}
public class SwitchToDemoAction extends AbstractAction {
MainUI mainUI;
UIModule uiModule;
public SwitchToDemoAction(MainUI mainUI, UIModule uiModule) {
super(uiModule.getName(), uiModule.getIcon());
this.mainUI = mainUI;
this.uiModule = uiModule;
}
public void actionPerformed(ActionEvent e) {
mainUI.setUI(uiModule);
}
}
class ToolBarPanel extends JPanel implements ContainerListener {
public boolean contains(int x, int y) {
Component c = getParent();
if (c != null) {
Rectangle r = c.getBounds();
return (x >= 0) && (x < r.width) && (y >= 0) && (y < r.height);
} else {
return super.contains(x, y);
}
}
public void componentAdded(ContainerEvent e) {
Container c = e.getContainer().getParent();
if (c != null) {
c.getParent().validate();
c.getParent().repaint();
}
}
public void componentRemoved(ContainerEvent e) {
Container c = e.getContainer().getParent();
if (c != null) {
c.getParent().validate();
c.getParent().repaint();
}
}
}
static Insets zeroInsets = new Insets(1, 1, 1, 1);
protected class ToggleButtonToolBar extends JToolBar {
public ToggleButtonToolBar() {
super();
}
JToggleButton addToggleButton(Action a) {
JToggleButton tb =
new JToggleButton(
(String) a.getValue(Action.NAME),
(Icon) a.getValue(Action.SMALL_ICON));
tb.setMargin(zeroInsets);
tb.setText(null);
tb.setEnabled(a.isEnabled());
tb.setToolTipText((String) a.getValue(Action.SHORT_DESCRIPTION));
tb.setAction(a);
add(tb);
return tb;
}
}
}

  
package com.account.ui;
import java.awt.BorderLayout;
import java.awt.Dimension;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class UIModule {
private MainUI mainUI;
private JPanel panel;
private String type;
private String iconPath;
public UIModule(MainUI mainUI) {
this(mainUI, null);
}
public UIModule(MainUI mainUI, String iconPath) {
this.mainUI = mainUI;
this.iconPath = iconPath;

panel = new JPanel();
panel.setLayout(new BorderLayout());

}
public JPanel getPanel() {
return panel;
}
public MainUI getMainUI() {
return mainUI;
}
public Icon getIcon() {
return createImageIcon(iconPath, "icon");
}
public ImageIcon createImageIcon(String filename, String description) {
String path = filename;
return new ImageIcon(getClass().getResource(path), description);
}
public String getName() {
return getType() + " Frame";
}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
public void mainImpl() {
JFrame frame = new JFrame(getName());
frame.getContentPane().setLayout(new BorderLayout());
frame.getContentPane().add(getPanel(), BorderLayout.CENTER);
getPanel().setPreferredSize(new Dimension(680, 600));
frame.pack();
frame.show();
}
public static void main(String[] args) {
UIModule mo = new UIModule(null);
mo.mainImpl();
}
}

Class extends UIModule

package com.account.ui;
import java.awt.BorderLayout;
import javax.swing.JButton;
import javax.swing.JPanel;
public class BasicSearch extends UIModule {
public BasicSearch(MainUI mainUI) {
super(mainUI, "search.jpg");
setType("Basic");
JPanel panel = getPanel();
panel.add(new JButton("Basic search"), BorderLayout.NORTH);

}
}