Check out example codes for "jcombobox java". It will help you in understanding the concepts better.

Code Example 1

// Java Program to create a simple JComboBox  
// and add elements to it 
import java.awt.event.*; 
import java.awt.*; 
import javax.swing.*; 
class solve extends JFrame implements ItemListener { 
  
    // frame 
    static JFrame f; 
  
    // label 
    static JLabel l, l1; 
  
    // combobox 
    static JComboBox c1; 
  
    // main class 
    public static void main(String[] args) 
    { 
        // create a new frame 
        f = new JFrame("frame"); 
  
        // create a object 
        solve s = new solve(); 
  
        // set layout of frame 
        f.setLayout(new FlowLayout()); 
  
        // array of string contating cities 
        String s1[] = { "Jalpaiguri", "Mumbai", "Noida", "Kolkata", "New Delhi" }; 
  
        // create checkbox 
        c1 = new JComboBox(s1); 
  
        // add ItemListener 
        c1.addItemListener(s); 
  
        // create labels 
        l = new JLabel("select your city "); 
        l1 = new JLabel("Jalpaiguri selected"); 
  
        // set color of text 
        l.setForeground(Color.red); 
        l1.setForeground(Color.blue); 
  
        // create a new panel 
        JPanel p = new JPanel(); 
  
        p.add(l); 
  
        // add combobox to panel 
        p.add(c1); 
  
        p.add(l1); 
  
        // add panel to frame 
        f.add(p); 
  
        // set the size of frame 
        f.setSize(400, 300); 
  
        f.show(); 
    } 
    public void itemStateChanged(ItemEvent e) 
    { 
        // if the state combobox is changed 
        if (e.getSource() == c1) { 
  
            l1.setText(c1.getSelectedItem() + " selected"); 
        } 
    } 
}

Code Example 2

String[] petStrings = { "Bird", "Cat", "Dog", "Rabbit", "Pig" };

//Create the combo box, select item at index 4.
//Indices start at 0, so 4 specifies the pig.
JComboBox petList = new JComboBox(petStrings);
petList.setSelectedIndex(4);
petList.addActionListener(this);

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