如何在jtextarea中选择行

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class TextAreaDemo extends JFrame {
    private JTextArea textArea;

    public TextAreaDemo() {
        setTitle("TextArea Demo");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLayout(new BorderLayout());

        textArea = new JTextArea();
        JScrollPane scrollPane = new JScrollPane(textArea);
        add(scrollPane, BorderLayout.CENTER);

        JButton selectButton = new JButton("Select Line");
        selectButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                selectCurrentLine();
            }
        });
        add(selectButton, BorderLayout.SOUTH);

        pack();
        setLocationRelativeTo(null);
        setVisible(true);
    }

    private void selectCurrentLine() {
        String text = textArea.getText();
        int caretPosition = textArea.getCaretPosition();
        int start = 0;
        int end = 0;

        // 分割文本为行
        String[] lines = text.split("\n");

        // 获取光标所在行的索引
        int currentLineIndex = 0;
        for (int i = 0; i < lines.length; i++) {
            if (caretPosition >= start && caretPosition <= end) {
                currentLineIndex = i;
                break;
            }
            start = end + 1;
            end = start + lines[i].length();
        }

        // 获取光标所在行的起始和结束位置
        start = 0;
        end = 0;
        for (int i = 0; i < currentLineIndex; i++) {
            start = end + 1;
            end = start + lines[i].length();
        }

        // 设置选中文本的起始和结束位置
        textArea.setSelectionStart(start);
        textArea.setSelectionEnd(end);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new TextAreaDemo();
            }
        });
    }
}