This is a tutorial in which we will going to create a program that has the JComboBox component/control using Java.

So, now let's start this tutorial!

1. Open JCreator or NetBeans and make a java program with a file name of jComboBoxComponent.java.

2. Import the following packages:

1. import
   
   java.awt.*
   
   ;
   
   //used to access the flowlayout
   
2. import
   
   javax.swing.*
   
   ;
   
   //used to access the JFrame and JComboBox class
   

3. The jComboBoxComponent classname must extends the JFrame to have the container of the components used. Have also the following variables for the JComboBox below:

1. String
   
   days[
   
   ]
   
   =
   
   {
   
   "Monday"
   
   , "Tuesday"
   
   , "Wednesday"
   
   , "Thursday"
   
   , "Friday"
   
   }
   
   ;
   
   //string array of days to be added to combobox
   
2. JComboBox
   
   cbo =
   
   new
   
   JComboBox
   
   (
   
   days)
   
   ;
   
   //instantiate a combobox which contains the value of days variable from the string array
   

We have created a String array of days to be added to the combobox.

4. Now, create a constructor to add the JComboBox to the frame as well as its layout and visibility.

Another way of adding items to the ComboBox is to have the addItem method. As you can see the String array of days variable above has only Monday to Friday. To add another item, have this code below:

1. cbo.addItem
   
   (
   
   "Saturday"
   
   )
   
   ;
   
   // add the value of Saturday to the combobox
   
2. cbo.addItem
   
   (
   
   "Sunday"
   
   )
   
   ;
   
   // add the value of Sunday to the combobox
   

Add the JComboBox to the frame using the add method and have it with the flowlayout layout of the frame.

1. getContentPane(
   
   )
   
   .add
   
   (
   
   cbo)
   
   ;
   
   //add the combobox to JFrame
   
2. getContentPane(
   
   )
   
   .setLayout
   
   (
   
   new
   
   FlowLayout
   
   (
   
   )
   
   )
   
   ;
   
   // have FlowLayout of JFrame
   

Then pack the frame so that the component/control will be seen directly to the frame. Also set its visibility to true and have it the close operation to exit.

1. pack(
   
   )
   
   ;
   
   //pack the frame
   
2. setVisible(
   
   true
   
   )
   
   ;
   
   //set visibility to true
   
3. setDefaultCloseOperation(
   
   JFrame
   
   .EXIT_ON_CLOSE
   
   )
   
   ;
   
   //exit after clicking the close button
   

Output:

Here's the full code of this tutorial:

1. import
   
   java.awt.*
   
   ;
   
   //used to access the flowlayout
   
2. import
   
   javax.swing.*
   
   ;
   
   //used to access the JFrame and JComboBox class
   
3. 
   
4. public
   
   class
   
   jComboBoxComponent extends
   
   JFrame
   
   {
   
5. 
   
6. String
   
   days[
   
   ]
   
   =
   
   {
   
   "Monday"
   
   , "Tuesday"
   
   , "Wednesday"
   
   , "Thursday"
   
   , "Friday"
   
   }
   
   ;
   
   //string array of days to be added to combobox
   
7. JComboBox
   
   cbo =
   
   new
   
   JComboBox
   
   (
   
   days)
   
   ;
   
   //instantiate a combobox which contains the value of days variable from the string array
   
8. 
   
9. public
   
   jComboBoxComponent(
   
   )
   
   {
   
   //constructor
   
10. 
    
11. 
    
12. cbo.addItem
    
    (
    
    "Saturday"
    
    )
    
    ;
    
    // add the value of Saturday to the combobox
    
13. cbo.addItem
    
    (
    
    "Sunday"
    
    )
    
    ;
    
    // add the value of Sunday to the combobox
    
14. 
    
15. getContentPane(
    
    )
    
    .add
    
    (
    
    cbo)
    
    ;
    
    //add the combobox to JFrame
    
16. getContentPane(
    
    )
    
    .setLayout
    
    (
    
    new
    
    FlowLayout
    
    (
    
    )
    
    )
    
    ;
    
    // have FlowLayout of JFrame
    
17. pack(
    
    )
    
    ;
    
    //pack the frame
    
18. setVisible(
    
    true
    
    )
    
    ;
    
    //set visibility to true
    
19. setDefaultCloseOperation(
    
    JFrame
    
    .EXIT_ON_CLOSE
    
    )
    
    ;
    
    //exit after clicking the close button
    
20. }
    
21. 
    
22. public
    
    static
    
    void
    
    main(
    
    String
    
    arg[
    
    ]
    
    )
    
    {
    
23. new
    
    jComboBoxComponent(
    
    )
    
    ;
    
    //call the constructor
    
24. }
    
25. }
    

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IT Instructor/System Developer/Android Developer/Freelance Programmer
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