语法错误不知为何故？

写了下面一段代码，但是在这两个地方老是报错，不知为何故：

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

public class FocusEvent extends JFrame{
  JButton jb = new JButton("FocusTest");
  jb.setBackground(Color.green);//此处“Syntax error on token "setBackground", Identifier expected after this token”
  jb.addFocusListener(new FocusListener(){//此处“Syntax error on token "addFocusListener", = expected after this token”
    public void focusGained(FocusEvent e){
      jtf.setEditable(true);
    }
  });
  public FocusEvent(){
    setLayout(new FlowLayout());
    add(jb);
    add(jtf,JLabel.RIGHT);
  }

  final JTextField jtf = new JTextField();
  public static void main(String[] args){
    SwingConsole sc = new SwingConsole();
    sc.run(new FocusEvent(),500,300);
  }
}