Updating a JCombo Box at run time

[Umesh Pandey]

Hi,

I have three combo boxes, i am trying to update the Values of second combo box depending on the Value of First Combo box, Initially second and third JComobo Boxes are set not to be enabled. for ex: if 'A' is selected in first Combo Box then Second should get enabled and will display values related to 'A'.


I am having problem in enabling the Second Combo Box, I have attached Action Listener to both the Combo Box

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import java.io.File;

import javax.swing.*;


public class GUI implements ActionListener{

public static String SourcePath = "D:\\UmeshDocs";
	
	public JComboBox module1 = new JComboBox();
	public JComboBox module2 = new JComboBox();
	public JComboBox module3 = new JComboBox();
	JPanel panel1 = new JPanel(new FlowLayout(FlowLayout.CENTER));
	JFrame frame = new JFrame("BatchRunner: Utility to RUN the OpenScript Automation in a Batch");
	/**
	 * @param args
	 */
//	public static void main(String[] args) {
//		// TODO Auto-generated method stub
//
//	}
	
	public void showGUI(){
		
		
		String[] PRJ_Modules = {"Student Records","Financial Aid","Campus Community",
								"Student Financials","Academic Advisement"};
		
		// Creating the Frame Object
		
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setLayout(new FlowLayout(FlowLayout.LEFT));
		frame.setUndecorated(true);
		frame.getRootPane().setWindowDecorationStyle(JRootPane.PLAIN_DIALOG);
		
		// Creating the Panel Object
		
		panel1.setPreferredSize(new Dimension(800,800));
		  
		// Creating the Combo Box Objects
		
		module1.setPreferredSize(new Dimension(200,30));
		module1.setActionCommand("module1Selection");
				
		module2.setPreferredSize(new Dimension(200,30));
		module2.setActionCommand("module2Selection");
//		module2.setEditable(false);
		
		module3.setPreferredSize(new Dimension(200,30));
		module3.setActionCommand("module3Selection");
		
		module1.addActionListener((ActionListener) this);
		module2.addActionListener((ActionListener) this);
		
		// Creating the Label Objects
		JLabel label1 = new JLabel("Select the Module from the List Below");
		label1.setPreferredSize(new Dimension(300,100));
		
		JLabel label2 = new JLabel("Select the Sub Module from the List Below");
		label2.setPreferredSize(new Dimension(300,100));
		
		JLabel label3 = new JLabel("Select the Feature from the List Below");
		label3.setPreferredSize(new Dimension(300,100));
		  
		// Adding Components to the Panel Object
		panel1.add(label1);
		panel1.add(module1);
		  
		panel1.add(label2);
		panel1.add(module2);
		
		panel1.add(label3);
		panel1.add(module3);
		
		
		// Adding Panel to the Frame and setting the Frame Size to Full Screen
		frame.add(panel1);		 
		Toolkit tk = Toolkit.getDefaultToolkit();  
		frame.setSize((int)tk.getScreenSize().getWidth(),(int)tk.getScreenSize().getHeight());
		frame.setVisible(true);
	
}
		
	
	@Override
	public void actionPerformed(ActionEvent ie) {
		String selectedItem = null;
		String SourcePath = "D:\\Umesh Docs";
		int i = 0;
		String[] S ;
		
//		JComboBox cb = (JComboBox)ie.getSource();
//		selectedItem = (String)cb.getSelectedItem();
		
		System.out.println(ie.getActionCommand());
		if(ie.getActionCommand().equalsIgnoreCase("module1Selection"))
		{
			System.out.println("Module1 ComboBox is Selected");
			
			System.out.println(module1.getSelectedItem());
			selectedItem = module1.getSelectedItem().toString();
			System.out.println(S);
			module2.setEnabled(true);
			
			System.out.println("Module2 is Enabled now");
			module2.addItem("A's Siblings");

//			frame.repaint();
		}
		else if(ie.getActionCommand().equalsIgnoreCase("module2Selection"))
		{
			System.out.println("Module2 ComboBox is Selected");
		}else
			{
				System.out.println("Module3 ComboBox is Selected");
			}
			
	}

}

[Michael Dunn]

> i am trying to update the Values of second combo box depending on the Value of First Combo box,

use the comboBox's model to do that
i.e. whatever's selected in combo1 creates a 'model' of items for display in combo2,
that model is then set as combo2's model.

for enabling/disabling have you thought of displaying no items in combo2 and combo3,
then setting their respective models, on selection of combo1 item.
(you would need to change from FlowLayout to perhaps GridLayout,
otherwise their sizes will look weird, and then change when models set)

[Kemal Sokolovic]

Umesh Pandey, please UseCodeTags (<- click) when posting your code. With proper indentation you will make your code a lot easier to read. I have added them for you this time.

And welcome to the Ranch!

[Umesh Pandey]

Hi Michael,

Thanks for your suggestion, but can you please post some example how to create Combo Box Models. I am a beginner in this and has very little idea about Swing programming.

Regards,
Umesh

[Darryl Burke]

There's a tutorial linked from the API for JComboBox. Have you gone through it?

[Darryl Burke]

Michael Dunn wrote:(you would need to change from FlowLayout to perhaps GridLayout,
otherwise their sizes will look weird, and then change when models set)

Or set an appropriate prototypeDisplayValue.

[Kemal Sokolovic]

Actually, the Tutorial is a good place in general, since the OP has stated not to have experience with Swing.