import javax.swing.*;
import java.awt.event.*;

public class AddRemoveItemFromCombo{
	JComboBox combo;
	JTextField txtBox;
	public static void main(String[] args){
		AddRemoveItemFromCombo ar = new AddRemoveItemFromCombo();
	}

	public AddRemoveItemFromCombo(){
		JFrame frame = new JFrame("Add-Remove Item of a Combo Box");
		String items[] = {"Java", "JSP", "PHP", "C", "C++"};
		combo = new JComboBox(items);
		JButton button1 = new JButton("Add");
		txtBox = new JTextField(20);
		button1.addActionListener(new ActionListener(){
			public void actionPerformed(ActionEvent e){
				if (!txtBox.getText().equals("")){
					int a = 0;
					for(int i = 0; i < combo.getItemCount(); i++){
						if(combo.getItemAt(i).equals(txtBox.getText())){
							a = 1;
							break;
						}
					}
					if (a == 1)
						JOptionPane.showMessageDialog(null,"Combo has already this item.");
					else
						combo.addItem(txtBox.getText());
				}
				else{
					JOptionPane.showMessageDialog(null,"Please enter text in Text Box");
				}
			}
		});
		JButton button2 = new JButton("Remove");
		button2.addActionListener(new ActionListener(){
			public void actionPerformed(ActionEvent e){
				if (combo.getItemCount() > 0)
					combo.removeItemAt(0);
				else
					JOptionPane.showMessageDialog(null,"Item not available");
			}
		});
		JPanel panel = new JPanel();
		JPanel panel1 = new JPanel();
		panel.add(txtBox);
		panel.add(combo);
		panel.add(button1);
		panel.add(button2);
		frame.add(panel);
//		frame.add(panel1);
		frame.setSize(400, 400);
		frame.setVisible(true);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

	}
}