A DESCRIPTION OF THE PROBLEM :
If JComboBox.setSelectedItem is called twice before it becomes visible, then on the first popup show its scroll does not contain current selected item.


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Run test code
2. Click on the combo box to show the popup


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Current selected item should be visible in popup on the first open.
ACTUAL -
Current selected item is not visible in popup (you have to scroll up to see it).

---------- BEGIN SOURCE ----------
import javax.swing.*;
import java.awt.*;

public class DropDownTest {

    public static void main(String[] args) {
        String[] months = new String[12];
        for (int i = 0; i < 12; i++)
            months[i] = String.valueOf(i + 1);
        JComboBox ch = new JComboBox(months);
        ch.setSelectedItem(months[3]);
        ch.setSelectedItem(months[2]);
        JFrame frame = new JFrame();
        frame.add(ch, BorderLayout.CENTER);
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.setLocationRelativeTo(null);
        frame.pack();
        frame.setVisible(true);
    }
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
You can create DefaultComboBoxModel first:
        DefaultComboBoxModel<String> model = new DefaultComboBoxModel<>(months);
        model.setSelectedItem(months[3]);
        JComboBox<String> ch = new JComboBox<>(model);
        ch.setSelectedItem(months[2]);


FREQUENCY : always