Java Tutorial for Beginners - 43 - GUI - Setting up KeyListener, Keyboard Events, JLabel and Textbox

In this tutorial we will go over how to make our program respond to user input

[EJMedia]

Source:
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;

public class Gui extends JFrame implements KeyListener {
    
JTextField keyText = new JTextField(80);   
JLabel keyLabel = new JLabel("Press fire button");
    
Gui () { 
   
keyText.addKeyListener(this);
setSize(400, 400);  
setVisible(true);
setLocationRelativeTo(null);


BorderLayout layout = new BorderLayout();
setLayout(layout); 
add(keyLabel, BorderLayout.NORTH);
add(keyText, BorderLayout.CENTER);
}

public void keyTyped (KeyEvent e) {
      // not putting anything in this method
}
public void keyPressed (KeyEvent e) {
  

   int keyCode = e.getKeyCode();
    if (keyCode == KeyEvent.VK_F){
      
        keyLabel.setText("You pressed the fire button");
    } 
    else {
        keyLabel.setText("You pressed the wrong key");
    }   
          
}
public void keyReleased (KeyEvent txt) {
    // not putting anything in this method
}
public static void main(String[] args) {
    
Gui go = new Gui();

}
}

[saschaAi]

Thank you sir, a very clear explanation and also a splendid video !

[RenatoAlmeida]

Sir, thank you soo much! I've been helped by this tutorial. The only thing I've change was where I added the keylistener. I needed that all the jFrame was onfocus. So I put this lines on construct:

this.addKeyListener(this);
setFocusable(true);

With theses lines, the jTextField it's not necessary.
That was my problem, maybe it's the problem of someone else.

[tornikeonoprishvili]

10/10 "Best game ever" - IGN (srsly tho, good vid ;)

[APHAS]

EJ Media person man, i love your face. Thank you!

[Senshiii]

If i wanna check the CONTROL KEYS then what will VK follow?

[rudytrevino]

Almost what I'm looking for, except what if I wanted text frames to update depending on one another. Example: User enters "50" into TextField1(MPH) and TextField2 (KPH) automatically updates to show "80.46" or vise versa User could enter KPH and program calculates MPH? Thanks!

[regman]

Thank you very much for your informative and easy to understands tutorials .
I have three questions,
1. Is there any particular reason for using constructor instead of void method ?
2. If i recall correctly in tutorial 24 you mentioned commands within a constructor can be run without requiring a main method if there is a no user input, would have been possible to run this code without main method if there was no user input ?
3. Why our class needs to inherit from JFrame despite of having java.swing package imported?

[sakaabdulrahman]

In the last part of the code. you defined Gui go = new Gui ( ); but you never defined "go" earlier. I wrote the same line as yours but it is not working

[sraj]

Sir,
To which Class.Object are the following methods attached to?
setSize(400, 400);
setVisible(true);

Don't these need to be referenced as SomeObjectName.setSize(400, 400)? How come you refer to them using just the method name with arguments?
Also, unclear as to what setLayout(layout); means. Its invoking the setLayout method from which class on the layout object?

[eobardthawne]

I want use keypress java on different program but not work what should i do?

[tingtingy]

For this code when I ran it, it loaded an empty frame at runtime... but when I moved "setVisible(true);" to the end of the GUI constructor it works

[SorenBagley]

i keep getting an error message at the line---- message reads "incompatible types. Gui cannot be converted to KeyListener. Leaking this in constructor" anyone else having this problem? am I just making a silly mistake?

[karimaali]

sir i have 2 question 
the code what do it mean 
second 
when i call the constructor in the main method how it read all the class
thanks

[mollytaylor]

I typed up this lesson's code and posted it on github here:

[jorgeramos]

how come keycode is an int and not a char?

[voizer]

When are you going to make the mini game tutorials? :D

[manicho]

How many more videos do you plan on making for java? I need to learn java in 2 months so i need to know how many videos I need to watch to finish. EJ Media 

[TheSkyGamez]

it doesnt fire at all, with no errors

[stef]

instead of keyReleased i typed keyRelesed, and it took me about one hour to find the error. you should really put the source code in the description. often we will save a tons of time and nerves.