How to add and remove items in JComboBox in Java

In this tutorial, we are going to see how to add and remove items in JComboBox in Java. JComboBox is part of the Java Swing package. JComboBox inherits from the JComponent class. JComboBox displays a contextual menu which shows a list and the user can select an option in this specified list.

 

Java Program to Add and Remove Items in JComboBox:

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

class ComboBoxExample extends JFrame implements ItemListener, ActionListener {

    // frame 
    static JFrame frame; 
    // combobox 
    static JComboBox combobox; 
    // label 
    static JLabel l1, l2; 
    // textfield
    static JTextField text; 

    public static void main(String[] args) 
    {
        // create a new frame
        frame = new JFrame("Add and remove items"); 

        // create an object
        ComboBoxExample obj = new ComboBoxExample(); 
  
        // array of strings containing languages
        String langs[] = { "Java", "PHP", "Python", "C++", "Ruby" }; 
  
        // create a checkbox
        combobox = new JComboBox(langs); 

        // create textfield
        text = new JTextField(10); 

        // create add and remove buttons
        JButton b1 = new JButton("Add"); 
        JButton b2 = new JButton("Remove"); 

        // add action listener 
        b1.addActionListener(obj); 
        b2.addActionListener(obj); 
    
        // add ItemListener
        combobox.addItemListener(obj); 
  
        // create labels
        l1 = new JLabel("What is your favorite language? "); 
        l2 = new JLabel("[Java]"); 
  
        // set text color
        l2.setForeground(Color.blue); 
  
        // create a new panel
        JPanel p = new JPanel(); 

        // add combobox, textfield, button and labels to the panel
        p.add(l1);
        p.add(combobox); 
        p.add(l2); 
        p.add(text); 
        p.add(b1); 
        p.add(b2); 
    
        // add panel to frame
        frame.add(p); 

        // set the frame size
        frame.setSize(400, 200); 
        frame.setLayout(new GridLayout(2, 1));
        frame.show(); 
    } 
  
    // if the button is pressed
    public void actionPerformed(ActionEvent e) 
    { 
        String str = e.getActionCommand(); 
        if (str.equals("Add")) { 
            combobox.addItem(text.getText()); 
        } 
        else { 
            combobox.removeItem(text.getText()); 
        } 
    }
  
    public void itemStateChanged(ItemEvent e) 
    { 
        // check if the state of the combobox is modified
        if (e.getSource() == combobox) { 
            l2.setText(" ["+combobox.getSelectedItem()+"]"); 
        } 
    } 
}

Output:

MCQPractice competitive and technical Multiple Choice Questions and Answers (MCQs) with simple and logical explanations to prepare for tests and interviews.Read More