java不允许用户更改文本字段

Question

这个动作监听器是我代码的一部分

我想通过生成JOPTIONPANE对话框，防止用户在按下save按钮时更改jLabel1ISBN

我该怎么做

   jLabel1.setText("ISBN:");

    jLabel2.setText("Title:");

    jLabel3.setText("Year:");

    jLabel4.setText("Author:");

    title.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            titleActionPerformed(evt);
        }
    });

    save.setText("Save");
    save.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {



             try
           {

              Integer.parseInt( jLabel3.getText());
           }
           catch( Exception e)
           {
                JOptionPane.showMessageDialog(null, "You have to input a valid year!");
           }





            saveActionPerformed(evt);
        }
    });