Scala Swing事件中使用的反引号

val button = new JButton("Add text")
button.addActionListener(e => {
  val textField = e.getSource.asInstanceOf[JTextComponent]
  val text = textField.getText
  val expression = s"${textField.getText} $text"
  // 使用反引号包围表达式
  val result = scala.io.StdIn.readLine(s"Result: ${$expression}")
  textField.setText(result)
})