我正在尝试制作基于卡的应用程序。我一直在尝试遵循教程等。这是我的代码。到目前为止它非常简单。窗口显示，但里面的文本窗格没有。
/*
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*/
package professorphysinstall;
/**
*
* @author Kyle
*/
//Imports
import java.awt.CardLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextPane;
public class ProfessorPhysInstall {
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
// TODO code application logic here
//Variables
JFrame mainframe = new JFrame();
mainframe.setSize(500, 435);
JPanel cards = new JPanel(new CardLayout());
CardLayout cl = (CardLayout)(cards.getLayout());
mainframe.setTitle("Future Retro Gaming Launcher");
//Screen1
JPanel screen1 = new JPanel();
JTextPane TextPaneScreen1 = new JTextPane();
TextPaneScreen1.setEditable(false);
TextPaneScreen1.setBackground(new java.awt.Color(240, 240, 240));
TextPaneScreen1.setText("Welcome to the install wizard for Professor Phys!\n\nPlease agree to the following terms and click the next button to continue.");
TextPaneScreen1.setSize(358, 48);
TextPaneScreen1.setLocation(0, 0);
screen1.add(TextPaneScreen1);
mainframe.add(cards);
mainframe.setVisible(true);
}
}