[vc_row css_animation=”” row_type=”row” use_row_as_full_screen_section=”no” type=”full_width” angled_section=”no” text_align=”left” background_image_as_pattern=”without_pattern”][vc_column][vc_column_text]
Inputs from the keyboard in Java
[/vc_column_text][vc_separator type=”normal” up=”1″][vc_column_text css=”.vc_custom_1569958573252{background-color: #f6f6f6 !important;}”]
The class KeyAdapter in Java makes it possible to take inputs from the keyboard and use in your programs
[/vc_column_text][vc_empty_space height=”20px”][vc_column_text]
How to get inputs from the keyboard in Java?
In our game we want to allow the user to operate the game using the keyboard.
- A common way to accomplish this is to use Java’s built-in KeyAdapter class. It is a class used to receive input from the keyboard.
- Further, we will also use the built-in KeyEvent class. When a key is pressed, released, or typed, the relevant method activates in the listener object, and KeyEvent transferres then to it.
- Finally, we then create a new class of our own, KeyInput, which will handle all button presses in the game.
[/vc_column_text][vc_empty_space height=”30px”][vc_separator type=”normal”][vc_empty_space height=”15px”][vc_column_text]
How to use Keyadapter in Java?
Start by importing the classes:
import java.awt.event.KeyAdapter; import java.awt.event.KeyEvent;
Then we inherit the KeyAdapter class which allows you to take inputs from the keyboard (Remember inheritance?)
public class KeyInput extends KeyAdapter {
Game game;
Additionally, we create the constructor that takes the game object as instance variable
public KeyInput(Game game){
this.game = game;
}
Further, what will happen when a key is pressed? We attache pressing the button to the object called game
public void keyPressed(KeyEvent e){
game.keyPressed(e);
}
Finally, what happens when a key is released? We attach that command to the object called game
public void keyReleased(KeyEvent e){
game.keyReleased(e);
}
}
The complete set of code is:
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
public class KeyInput extends KeyAdapter {
Game game;
public KeyInput(Game game){
this.game = game;
}
public void keyPressed(KeyEvent e){
game.keyPressed(e);
}
public void keyReleased(KeyEvent e){
game.keyReleased(e);
}
}
[/vc_column_text][vc_empty_space height=”20px”][vc_column_text]
How use KeyEvent in Java?
We created our KeyInput class above that contains two methods, one for when we press a key and one for when we release a key. But now we want to make sure that the program actually detects which key is pressed.
Further, we will use the built-in methods VK_LEFT and VK_RIGHT found in KeyEvent to detect if it is the Left and Right arrow keys used.[/vc_column_text][vc_empty_space height=”40px”][vc_single_image image=”20081″ img_size=”large” alignment=”center” onclick=”link_image” qode_css_animation=””][vc_empty_space height=”40px”][vc_column_text]Let’s start by declaring a method for detecting if a key is pressed
public void keyPressed(KeyEvent e){
// New key press
int key = e.getKeyCode();
// If we press right
if (key == KeyEvent.VK_RIGHT) {
System.out.println("The right arrow key is pressed");
// Or, if we press left
} else if (key == KeyEvent.VK_LEFT) {
System.out.println("The left arrow key is pressed");
}
}
Additionally, what will happen when a key is released
public void keyReleased(KeyEvent e){
// New key has been released
int key = e.getKeyCode();
// If we release the right key
if(key == KeyEvent.VK_RIGHT){
System.out.println("The right arrow key is released");
}
// If we release the left key
else if(key == KeyEvent.VK_LEFT){
System.out.println("The left arrow key is released");
}
}
Note, we can of course do the same for other keys. The Oracle KeyEvent page lists commands for the other keys
Finally, the complete set of code is:
public void keyPressed(KeyEvent e){
// New key press
int key = e.getKeyCode();
// If we press right
if (key == KeyEvent.VK_RIGHT) {
System.out.println("The right arrow key is pressed");
// Or, if we press left
} else if (key == KeyEvent.VK_LEFT) {
System.out.println("The left arrow key is pressed");
}
}
public void keyReleased(KeyEvent e){
// New key has been released
int key = e.getKeyCode();
// If we release the right key
if(key == KeyEvent.VK_RIGHT){
System.out.println("The right arrow key is released");
}
// If we release the left key
else if(key == KeyEvent.VK_LEFT){
System.out.println("The left arrow key is released");
}
}
[/vc_column_text][vc_empty_space height=”30px”][vc_column_text]
Previous Page | Next Page
[/vc_column_text][vc_empty_space][/vc_column][/vc_row]
