Java KeyListener：KeyTyped Backspace，Esc作为输入

Question

在KeyTyped方法内部，如何判断是否按下了Backspace或Esc ？

Answer 1

Assuming you have attached the KeyListener properly and have implemented the methods required for that KeyListener, to detect specific key-presses simply add the following code:

public void keyReleased(KeyEvent ke) 
{
    if(ke.getKeyCode() == KeyEvent.VK_BACK_SPACE)
    {  
        //code to execute if backspace is pressed
    }

    if(ke.getKeyCode() == KeyEvent.VK_ESCAPE)
    {
        //code to execute if escape is pressed
    }
}

The KeyEvent class javadocs can be found at the following link: KeyEvent javadocs .
There you can find a list of all of the Java virtual keycodes used to detect keyboard input when implementing Java KeyListeners and KeyEvents. More information about KeyListeners can be found here: How to Write a Key Listener . To use the keyTyped method as asked, see gangqinlaohu's answer .

Answer 2

http://www.fileformat.info/info/unicode/char/8/index.htm

When arg0.getKeyChar() is cast to an int: (int)arg0.getKeyChar() , The backspace key comes up with the value 8, and the Esc key comes up with the value 27.

Answer 3

I understand this is a very old subject, but I wanted to add an answer that I found helped me greatly with the same issue.

I'm making a chat input for a Java program, and its better to use KeyTyped as opposed to pressed and released (as it excluded the need to filter most characters). Anyways I wanted to make backspace delete characters, but the .getKeyCode() always returned 0 as per the documentation. However, you can use .getKeyChar() to return the character (probably will appear as a square box), and the escape character '\\b' to do a comparison.

if(tmp.getKeyChar().equals('\b')) { ... }

Answer 4

Only for java 7 / jdk1.7 and above: In case you are checking against event.getKeyCode() , try the event.getExtendedKeyCode() method. In case of the back-space it will return the proper code (in this case, 8) instead of a plain 0. That way there is no need to check against \\b :

if (e.getExtendedKeyCode() == KeyEvent.VK_BACK_SPACE) {
    System.out.println("Backspace pressed");
}

Answer 5

您还可以在keyTyped使用e.getExtendedKeyCode() ，并返回看似正确的非零值。

Answer 6

Personally, I prefer to use the KeyPressed event for keys other than letters/numbers, as when you're typing the Backspace or Enter keys, nothing is actually being typed per say. Here's what I did that worked (make sure KeyCode and KeyEvent are imported from javafx.scene.input)!

MyTextArea.addEventHandler(KeyEvent.KEY_PRESSED, new EventHandler<KeyEvent>(){
    @Override
    public void handle(KeyEvent event) {
        if (event.getCode().equals(KeyCode.BACK_SPACE)){
            System.out.println("Success");
        }
    }
});

Let me know if this worked for you :)

Answer 7

Check below code, I hope it will work for you.

@FXML
public void keyPresses(KeyEvent ke) 
{
    if (ke.getCode().equals(KeyCode.BACK_SPACE)) {
        System.out.println("It Works Backspace pressed..!");
    }
}