如何最好地完成Java类之间的消息传递?

public class PrintStatusTask extends Thread {
    PrintStatusTask(String name) {
        this.name = name;
    }
    private void sendMessage(String s) {
        // TODO: send message to jTextArea
    }
    public void run() {
        ...
        sendMessage("Any message");
        ...

下面是一个从JFrame写入JScrollPane的示例:

public class Controller extends javax.swing.JFrame implements Observer {
    ...
    jTextArea.append(s);    
    ...