This is a tutorial in which we will going to create a program that has the JTextField Component using Java. The JTextField is a basic text control component that enables the user to type a small amount of text.

So, now let's start this tutorial!

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

2. Import the following packages:

1. JFrame
   
   frame =
   
   new
   
   JFrame
   
   (
   
   "JTextField Component"
   
   )
   
   ;
   
2. 
   
3. JLabel
   
   name =
   
   new
   
   JLabel
   
   (
   
   "Enter name: "
   
   )
   
   ;
   
4. JTextField
   
   txtName =
   
   new
   
   JTextField
   
   (
   
   20
   
   )
   
   ;
   

We have created a JTextField component with variable named txtName. The 20 inside the JTextField components indicate the number of characters allowed on the text field.

To create the size of the textfield, we will use the setPreferredSize method and will access the Dimension class.

1. txtName.setPreferredSize
   
   (
   
   new
   
   Dimension
   
   (
   
   100
   
   , 30
   
   )
   
   )
   
   ;
   

The 100 is the width of the textfield dimension and 30 is the height.

3. Now, we will add a KeyEvent and KeyListener to the textfield. We will have a text field that if we input text in there, it will automatically converted into uppercase letters. Have this code below:

1. txtName.addKeyListener
   
   (
   
   new
   
   KeyAdapter
   
   (
   
   )
   
   {
   
2. public
   
   void
   
   keyReleased(
   
   KeyEvent
   
   e)
   
   {
   
3. JTextField
   
   textField =
   
   (
   
   JTextField
   
   )
   
   e.getSource
   
   (
   
   )
   
   ;
   
4. String
   
   text =
   
   textField.getText
   
   (
   
   )
   
   ;
   
5. textField.setText
   
   (
   
   text.toUpperCase
   
   (
   
   )
   
   )
   
   ;
   
6. }
   

We have created a text variable for our TextField. The getText method here gets the string input of the user. The setText method will set the text to the textfield and it will be converted into uppercase letters using toUpperCase method.

4. Now, add the JLabel variable to the frame using the default BorderLayout of West position and the JTextField variable using the default BorderLayout of South position of the getContentPane method. Lastly, set the size, visibility, and the close operation of the frame. Have this code below:

1. frame.getContentPane
   
   (
   
   )
   
   .add
   
   (
   
   name,"West"
   
   )
   
   ;
   
2. frame.getContentPane
   
   (
   
   )
   
   .add
   
   (
   
   txtName,"South"
   
   )
   
   ;
   
3. frame.setSize
   
   (
   
   400
   
   , 200
   
   )
   
   ;
   
4. frame.setVisible
   
   (
   
   true
   
   )
   
   ;
   
5. frame.setDefaultCloseOperation
   
   (
   
   JFrame
   
   .EXIT_ON_CLOSE
   
   )
   
   ;
   

Output:



Here's the full code of this tutorial:

1. import
   
   java.awt.*
   
   ;
   
   //used to access the Dimension class
   
2. import
   
   java.awt.event.*
   
   ;
   
   //used to access the KeyAdapter and KeyEvent class
   
3. import
   
   javax.swing.*
   
   ;
   
   //used to access the JFrame, JLabel, and JTextField class
   
4. 
   
5. 
   
6. public
   
   class
   
   jTextFieldComponent {
   
7. 
   
8. public
   
   static
   
   void
   
   main(
   
   String
   
   [
   
   ]
   
   args)
   
   {
   
9. JFrame
   
   frame =
   
   new
   
   JFrame
   
   (
   
   "JTextField Component"
   
   )
   
   ;
   
10. 
    
11. 
    
12. JLabel
    
    name =
    
    new
    
    JLabel
    
    (
    
    "Enter name: "
    
    )
    
    ;
    
13. JTextField
    
    txtName =
    
    new
    
    JTextField
    
    (
    
    20
    
    )
    
    ;
    
14. 
    
15. txtName.setPreferredSize
    
    (
    
    new
    
    Dimension
    
    (
    
    100
    
    , 30
    
    )
    
    )
    
    ;
    
16. 
    
17. 
    
18. txtName.addKeyListener
    
    (
    
    new
    
    KeyAdapter
    
    (
    
    )
    
    {
    
19. public
    
    void
    
    keyReleased(
    
    KeyEvent
    
    e)
    
    {
    
20. JTextField
    
    textField =
    
    (
    
    JTextField
    
    )
    
    e.getSource
    
    (
    
    )
    
    ;
    
21. String
    
    text =
    
    textField.getText
    
    (
    
    )
    
    ;
    
22. textField.setText
    
    (
    
    text.toUpperCase
    
    (
    
    )
    
    )
    
    ;
    
23. }
    
24. 
    
25. 
    
26. }
    
    )
    
    ;
    
27. frame.getContentPane
    
    (
    
    )
    
    .add
    
    (
    
    name,"West"
    
    )
    
    ;
    
28. frame.getContentPane
    
    (
    
    )
    
    .add
    
    (
    
    txtName,"South"
    
    )
    
    ;
    
29. frame.setSize
    
    (
    
    400
    
    , 200
    
    )
    
    ;
    
30. frame.setVisible
    
    (
    
    true
    
    )
    
    ;
    
31. frame.setDefaultCloseOperation
    
    (
    
    JFrame
    
    .EXIT_ON_CLOSE
    
    )
    
    ;
    
32. 
    
33. }
    
34. }
    

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Best Regards,

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