将命令输出打印到文本区域/文本面板 - JSch

Question

该程序是JSch的一部分，之前用于读取输出内容然后将其打印到控制台，但我已经制作了具有textPanel的UI，我想将提取的内容写入文本区域。但我得到Null指针异常。我调用textPanel的方式有问题。

JumpHosts - http://www.jcraft.com/jsch/examples/JumpHosts.java.html（完整计划）

            byte[] tmp = new byte[1024];
            while (true) {
                while (in.available() > 0) {
                    int i = in.read(tmp, 0, 1024);
                    if (i < 0)
                        break;
                    //System.out.print(new String(tmp, 0, i));
                    textPanel.appendText(new String(tmp, 0, i));
                }
                if (channel.isClosed()) {
                    //System.out.println("exit-status: " + channel.getExitStatus());
                    textPanel.appendText(new String("exit-status: " + channel.getExitStatus()));
                    break;
                }
                try {
                    Thread.sleep(1000);
                } catch (Exception ee) {
                    System.out.println(ee);
                }
            }`

文字面板代码：

public class TextPanel extends JPanel {

private JTextArea textArea;

public TextPanel(){

    setLayout(new BorderLayout());

    textArea = new JTextArea();

    add(new JScrollPane(textArea),BorderLayout.CENTER);
}

public void appendText(String tmp){

    textArea.append(tmp);

}

文本面板在MainFrame类中初始化：

public class MainFrame extends JFrame{

private TextPanel textPanel;
private Toolbars toolbar;
private FormPanel formPanel;;

public MainFrame() {

    super("ABC");

    setLayout(new BorderLayout());

    //setJMenuBar(createMenuBar());

    textPanel = new TextPanel();
    toolbar = new Toolbars();
    formPanel = new FormPanel();

    toolbar.setStringListener(new StringListeners() {
        public void textEmitter(String text) {
            textPanel.appendText(text);
        }
    });

    formPanel.setFormListener(new FormListener(){
        public void formEventOccured(FormEvent e){
            String name = e.getName();
            String occupation = e.getOccupation();

            textPanel.appendText(name + " : " + occupation + "\n");

        }       
    });

    add(textPanel,BorderLayout.CENTER);
    add(toolbar,BorderLayout.NORTH);
    add(formPanel,BorderLayout.WEST);

    setVisible(true);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setMinimumSize(new Dimension(500, 400));
    setSize(600, 500);

}