final JTextField jtf = new JTextField(20);
        JButton jbutton_ok = new JButton("ok!");
        JButton jbutton_no = new JButton("no!");
        jbutton_ok.addActionListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent e) {
                if(e.getActionCommand().equals("ok!")){
                    System.out.println(jtf.getText());//不加final这里会报错
                }
            }
        });

JButton jbutton_ok = new JButton("ok!");
        JButton jbutton_no = new JButton("no!");
        jbutton_ok.addActionListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent e) {
                if(e.getActionCommand().equals("ok!")){
                    System.out.println(jtf.getText());//不加final这里会报错
                }
            }
        });
//所有方法外
private javax.swing.JTextField jtf = new javax.swing.JTextField(20);