Jpanel在添加JTextFile的组件时错误

import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.*;
import javax.swing.*;
public class MyClientP extends JFrame{
private JTextArea ta=new JTextArea();
JScrollPane sp=new JScrollPane(ta);
private JTextField tf=new JTextField();
public JPanel jp=new JPanel(new FlowLayout());
getContentPane.add(port,BorderLayout.CENTER);
JTextField port=new JTextField("Port",6);
JTextField domain=new JTextField("Host");
jp.add(domain);
jp.add(new JButton("Connecte"),);

Socket Client=null;
private PrintWriter writer=null;
Container c;
public MyClientP(String title){
super(title);
c=this.getContentPane();

//c.add(sp,"Center");
c.setLayout(new BorderLayout());
c.add(jp,"North");
c.add(sp,BorderLayout.CENTER);
c.add(tf,"South");
tf.addActionListener(new ActionListen());
ta.setLineWrap(true);
setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
}
class ActionListen implements ActionListener{
public void actionPerformed(ActionEvent e){
writer.println(tf.getText());
ta.append(tf.getText()+"\n");
tf.setText("");

}
}

private void Connect(){
ta.append ("尝试连接...");
try{
Client=new Socket("localhost",1080);
writer=new PrintWriter(Client.getOutputStream(),true);
ta.append("完成连接\n");

}catch(Exception e){
e.printStackTrace();

}
}
public static void main(String[] args){
MyClientP Mclient=new MyClientP("Client");
Mclient.setVisible(true);
Mclient.setSize(200,300);
Mclient.Connect();

}
}
想在Jpanel定义的jp中添加port（JTextField类型的）但是应用了jp.add(port)总是弹出非法标示的错误，网上找了下用了this.getContentPanel.add(port)也是不行，又说非法标示符和需要；不知道问题出在哪了，请高手相助。我用的是jcreator编译器！

MyClientP () {
JTextField port=new JTextField("Port",6);
getContentPane().add(port, BorderLayout.CENTER);

JTextField domain=new JTextField("Host");
jp.add(domain);
jp.add(new JButton("Connecte"));
}

PS：这些实现都必须在一个方法里面，不能在定义成员变量的地方直接实现其他功能，实现功能必须在方法里