请帮忙…

import java.awt.*;
import javax.swing.*;

@SuppressWarnings("serial")
public class test extends JFrame {

private static JTextArea referenceTextArea = new JTextArea(10,10);
private JPanel panel = new JPanel();

public test() {
    this.add(panel);
    panel.add(referenceTextArea);
}

public static void textTest() {
    referenceTextArea.setFont(new Font("Serif",Font.BOLD,15));
    referenceTextArea.append("line1");
    referenceTextArea.append("\n");

    referenceTextArea.setFont(new Font("Serif",Font.ITALIC,30));
    referenceTextArea.append("line2");
    referenceTextArea.append("\n");
}

public static void main(String[] args) {
    test frame = new test();
    frame.setVisible(true);
    frame.setSize(400,400);
    frame.setResizable(false);
    frame.setLocationRelativeTo(null);
    frame.setDefaultCloSEOperation(EXIT_ON_CLOSE);

    textTest();
}
}