JTextField在句号后限制输入

import javax.swing.*;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;

public class Main {
    public static void main(String[] args) {
        JFrame frame = new JFrame("JTextField限制输入示例");
        JTextField textField = new JTextField(20);

        textField.getDocument().addDocumentListener(new DocumentListener() {
            @Override
            public void insertUpdate(DocumentEvent e) {
                handleTextChange(e.getDocument());
            }

            @Override
            public void removeUpdate(DocumentEvent e) {
                handleTextChange(e.getDocument());
            }

            @Override
            public void changedUpdate(DocumentEvent e) {
                // 不处理
            }

            private void handleTextChange(Document document) {
                try {
                    String text = document.getText(0, document.getLength());
                    int dotIndex = text.indexOf(".");
                    if (dotIndex != -1 && document.getLength() - dotIndex > 1) {
                        document.remove(dotIndex + 1, document.getLength() - dotIndex - 1);
                    }
                } catch (BadLocationException ex) {
                    ex.printStackTrace();
                }
            }
        });

        frame.getContentPane().add(textField);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setVisible(true);
    }
}