What is JComboBox?
Nothing, it is just son of Choice in the AWT. Son doesn't mean that it is the sub class of Choice, instead i just mean that it does the same thing as the Choice in the AWT does. It allows only one item to choose. Mostly used to check Male/Female, Date of Birth (Day-Month-Year) etc.
The Example
import javax.swing.*;
import java.awt.*;
class JComboBoxExample extends JFrame
{
JComboBox jc1,jc2;
public JComboBoxExample()
{
setTitle("I am JComboBox Example!");
setSize(400,400);
setLayout(new FlowLayout());
setVisible(true);
setDefaultCloseOperation(EXIT_ON_CLOSE);
jc1=new JComboBox();
// Add items
jc1.addItem("Google");
jc1.addItem("Yahoo!");
jc1.addItem("Bing");
jc1.addItem("iGo4iT Search");
// Set 4th item selected
jc1.setSelectedIndex(3);
// Add jc1 to JFrame
add(jc1);
jc2=new JComboBox();
// Add items
jc2.addItem("Amazon.com");
jc2.addItem("eBay");
jc2.addItem("Walmart");
jc2.addItem("Best Buy");
// Make it editable
jc2.setEditable(true);
// Add jc to JFrame
add(jc2);
}
public static void main(String args[])
{
new JComboBoxExample();
}
}
Explanation
jc1,jc2: Both are the objects for the JComboBox.
addItem(""): Method of the JComboBox used to add items to it. The parameter to it is usually java.lang.Object, as per the requirement i have used String as it is a sub class of java.lang.Object class.
jc1.setSelectedIndex(3): As we know, index usually start from 0. Setting the selected index as 3 means that select the 4th item (0 1 2 3). Therefore, iGo4iT Search is selected.
jc2.setEditable(true): You might have observed, some drop downs can be edited i.e. the user is allowed to type something in it usually in autocomplete. It is obvious now i hope so, that the by passing true to the method lets the user type something in the JComboBox.
