Thread: JComboBox conditions?

package LockerSystem;
 
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.SQLException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.border.TitledBorder;
 
public class transfer extends JFrame {
 
    JComboBox cmbfrom, cmbto;
    JLabel lblfrom, lblto;
    JPanel Transfer;
    JButton btnok,btncancel;
 
    public transfer() {
 
 
 
        Transfer = new JPanel(new FlowLayout());
        Transfer.setBounds(5, 15, 275, 120);
        Transfer.setLayout(null);
        Transfer.setBorder(BorderFactory.createTitledBorder(null, "Transfer Locker", TitledBorder.LEFT, TitledBorder.TOP, Font.getFont("batang", null), Color.BLACK));
 
        lblfrom = new JLabel("From:");
        lblfrom.setBounds(50, 30, 70, 25);
        Transfer.add(lblfrom);
 
        lblto = new JLabel("To:");
        lblto.setBounds(50, 70, 70, 25);
        Transfer.add(lblto);
 
        final String[] program1 = {"Locker 1", "Locker 2", "Locker 3", "Locker 4", "Locker 5"};
 
        cmbfrom = new JComboBox(program1);
        cmbfrom.setBounds(110, 30, 100, 25);
        Transfer.add(cmbfrom);
 
        cmbto = new JComboBox(program1);
        cmbto.setBounds(110, 70, 100, 25);
        Transfer.add(cmbto);
 
 
 
        btnok = new JButton("Ok");
        btnok.setBounds(110, 140, 80, 25);
        add(btnok);
 
        btncancel = new JButton("Cancel");
        btncancel.setBounds(195, 140, 80, 25);
        add(btncancel);
 
 
        Container cp = this.getContentPane();
cp.setLayout(null);
        cp.add(Transfer);
 
 
 
    }
 
    public void run() {
        setBounds(0, 0, 300, 220);
        setTitle("Administrative Tools");
        setLocationRelativeTo(null);
        setVisible(true);
        setLayout(null);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
 
    public static void main(String[] main) {
        transfer t1 = new transfer();
        t1.run();
 
    }
}

My problem is how do you do it when I select item at "FROM : [comboBox]", that item I selected not listed in "TO : [comboBox]".

For example if i select "Locker 1" at the upper combobox, only the items "Locker 2", "Locker 3", "Locker 4", "Locker 5" will be available items to be selected at the lower combobox.

You would change the combo box's model -- remove that String from the second JComboBox's model. Another way is to give your second JComboBox a custom renderer, and in that renderer, make a cell's foreground color a color that makes it look disabled if it is the same String as was chosen by the first JComboBox. I'm not sure how to prevent the user from selecting it though.