java - (Java Swing) JTextField 更新 "too late"

Question

这是来自英尺<->米转换器的代码示例。我的问题:它不会更新当前输入，例如:如果 JTextField 中的文本是“50”，则 textField.getText() 仅给出字符串“5”，因此 双结果将是5.0。因此，JTextField 中的“5”会在 double result = Double.parseDouble(textField.getText());“Empty String”中给出错误。预先感谢您的回答!

public static void addKL(JTextField textField, JTextField textField2, String name) {

    textField.addKeyListener(new KeyAdapter() {
        public void keyPressed(KeyEvent evt) {
            if(evt.getKeyCode() == KeyEvent.VK_1||evt.getKeyCode() == KeyEvent.VK_2||evt.getKeyCode() == KeyEvent.VK_3||evt.getKeyCode() == KeyEvent.VK_4||evt.getKeyCode() == KeyEvent.VK_5||evt.getKeyCode() == KeyEvent.VK_6||evt.getKeyCode() == KeyEvent.VK_7||evt.getKeyCode() == KeyEvent.VK_9||evt.getKeyCode() == KeyEvent.VK_COLON||evt.getKeyCode() == KeyEvent.VK_BACK_SPACE                           ) {
                double result = Double.parseDouble(textField.getText());
                if(name=="ftFIELD") {
                    textField2.setText("" + result/3.2808);
                }
                else if(name=="mFIELD") {
                    textField2.setText("" + result*3.2808);
                }
            }
        }
    });
}

注意:如果 KeyEvent 无效，当然会缺少 else，但在这个错误未修复之前我不想继续编码。

Answer 1

您使用了错误的事件，请尝试使用keyReleased。还修复了字符串比较

    text.addKeyListener(new KeyAdapter() {
        public void keyReleased(KeyEvent evt) {
            if(evt.getKeyCode() == KeyEvent.VK_1||evt.getKeyCode() == KeyEvent.VK_2||evt.getKeyCode() == KeyEvent.VK_3||evt.getKeyCode() == KeyEvent.VK_4||evt.getKeyCode() == KeyEvent.VK_5||evt.getKeyCode() == KeyEvent.VK_6||evt.getKeyCode() == KeyEvent.VK_7||evt.getKeyCode() == KeyEvent.VK_9||evt.getKeyCode() == KeyEvent.VK_COLON||evt.getKeyCode() == KeyEvent.VK_BACK_SPACE                           ) {
                double result = Double.parseDouble(text.getText());

                if("ftFIELD".equals(name)) {
                    textField2.setText("" + result/3.2808);
                }
                else if("mFIELD".equals(name)) {
                    textField2.setText("" + result*3.2808);
                }
            }
        }
    });