KeyListener仅检测一次退格 [英] KeyListener detecting backspace only once

问题描述

我正在创建一个自定义文本字段(绘制文本而不是使用JTextField).我可以输入字符，但是退格键只能清除一个字符.然后，如果我再写一些东西，我可以再次删除一个字符.我不知道为什么.

I'm making a custom textfield (drawing the text instead of using JTextField). I can type the characters in, but the backspace only clears one character. Then if I write something more, I can delete one character again. I have no idea why.

KeyListener:

KeyListener:

class KeyController implements KeyListener {
        public void keyPressed(KeyEvent e) {
            if (!chat.getUsing()) {
                player.keyPressed(e);
            } else if (e.getKeyCode() == KeyEvent.VK_BACK_SPACE) {
                chat.keyTyped(e);
            }

            if (e.getKeyCode() == KeyEvent.VK_ENTER) {
                if (chat.getUsing()) {
                    chat.setUsing(false);
                } else {
                    chat.setUsing(true);
                }
            } 
        }

        public void keyReleased(KeyEvent e) {
            if (!chat.getUsing()) {
                player.keyReleased(e);
            }
        }

        public void keyTyped(KeyEvent e) {
            if (chat.getUsing() && e.getKeyCode() != KeyEvent.VK_BACK_SPACE) {
                chat.keyTyped(e);
            }
        }
    }

聊天对象中的keyTyped()方法:

The keyTyped() method in the chat object:

public void keyTyped(KeyEvent ev) {
        if (ev.getKeyCode() != KeyEvent.VK_BACK_SPACE) {
            currentText += ev.getKeyChar();
        } else {
            if (currentText.length() > 0) {
                currentText = currentText.substring(0, currentText.length() - 1);
            }
        }
    }

我正在绘制currentText字符串.

And I'm drawing out the currentText string.

推荐答案

尝试这个

 e.getKeyChar() != KeyEvent.VK_BACK_SPACE

代替

 e.getKeyCode() != KeyEvent.VK_BACK_SPACE

在keyTyped()方法中.

直接来自KeyEvent

getKeyChar方法始终返回有效的Unicode字符或CHAR_UNDEFINED.字符输入由KEY_TYPED事件报告:KEY_PRESSED和KEY_RELEASED事件不一定与字符输入关联.因此，保证getKeyChar方法的结果仅对KEY_TYPED事件有意义.

The getKeyChar method always returns a valid Unicode character or CHAR_UNDEFINED. Character input is reported by KEY_TYPED events: KEY_PRESSED and KEY_RELEASED events are not necessarily associated with character input. Therefore, the result of the getKeyChar method is guaranteed to be meaningful only for KEY_TYPED events.

对于按下键和释放键的事件，getKeyCode方法返回事件的keyCode.对于键类型的事件，getKeyCode方法始终返回VK_UNDEFINED . getExtendedKeyCode方法也可以与许多国际键盘布局一起使用.

For key pressed and key released events, the getKeyCode method returns the event's keyCode. For key typed events, the getKeyCode method always returns VK_UNDEFINED. The getExtendedKeyCode method may also be used with many international keyboard layouts.

有关更多信息，请在此处阅读有关关键事件的信息.

For more info read here about Key Event.

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