How to Listen to a Keyboard in Java

"Key listeners" in the Java programming language are triggered when you press or release a keyboard key. Keyloggers use key listeners to store the input each time the user presses a key. Programmers use key listener events to detect when a user types an incorrect character, such as by typing a letter in a text box that requires the user's phone number. Using the key listener you can alert the user to the incorrect character before he submits the form.

Instructions

1. Right-click the Java file you want to edit and select Open With. Click the Java compiler in the list of programs to load the code in the editor.

2. Include the listening class libraries available in Java. Copy and paste the following code to the top of your Java source code file:

   import java.awt.*;

   import java.awt.event.*;

3. Create the function that takes action when the user presses a key. In this example a message is sent to the Java form to display feedback for the user:

   public mylistener(String key ) {

   l1 = new Label ("Key Pressed!" ) ;

   }

4. Link the key listener function to the Java form. Type the following code to add the listener to key events on your form:

   addKeyListener ( this.mylistener ) ;

References

• Rose India: How to Use KeyListener