Java Swing - 如何从DefaultFormatterFactory创建JFormattedTextField

import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.text.NumberFormat;

import javax.swing.JButton;
import javax.swing.JFormattedTextField;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.text.DefaultFormatterFactory;
import javax.swing.text.NumberFormatter;

public class Main extends JPanel implements PropertyChangeListener {
  double amount = 100000;
  JFormattedTextField amountField;

  NumberFormat amountDisplayFormat;
  NumberFormat amountEditFormat;

  public Main() {
    super(new BorderLayout());
    amountDisplayFormat = NumberFormat.getCurrencyInstance();
    System.out.println(amountDisplayFormat.format(1200));
    amountDisplayFormat.setMinimumFractionDigits(0);
    amountEditFormat = NumberFormat.getNumberInstance();
    amountField = new JFormattedTextField(new DefaultFormatterFactory(
        new NumberFormatter(amountDisplayFormat), new NumberFormatter(
            amountDisplayFormat), new NumberFormatter(amountEditFormat)));
    amountField.setValue(new Double(amount));
    amountField.setColumns(10);
    amountField.addPropertyChangeListener("value", this);

    JPanel fieldPane = new JPanel(new GridLayout(0, 1));
    fieldPane.add(amountField);

    add(fieldPane, BorderLayout.LINE_END);
    add(new JButton("Hello"), BorderLayout.SOUTH);
  }

  public void propertyChange(PropertyChangeEvent e) {
    Object source = e.getSource();
    if (source == amountField) {
      amount = ((Number) amountField.getValue()).doubleValue();
      System.out.println("amount = " + amount);
      amountField.setValue(amount);
    }
  }
  public static void main(String[] args) {
    JFrame frame = new JFrame("FormatDemo");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(new Main());
    frame.pack();
    frame.setVisible(true);
  }
}