我试过很多方法，但还是不管用。我试图捕捉jtextfield中是否有数字，它将使字符串文本变为红色并弹出joption。但我的代码只有在两个jtextfield中都有数字时才会被捕获。我希望我的jtextfield只有字符和空格。
（jtf2和jtf3是jtextfield）

if(ae.getSource() == bcreate) // create
{
    String firstname;
    String lastname;
    String id;
    firstname = jtf2.getText();
    lastname = jtf3.getText();
    try
    {
        Integer.parseInt(jtf2.getText());
        jtf2.setForeground(Color.RED);

        Integer.parseInt(jtf3.getText());
        jtf3.setForeground(Color.RED);
        JOptionPane.showMessageDialog(null, "Please enter valid character","ERROR",JOptionPane.ERROR_MESSAGE);
    }
    catch(NumberFormatException w)
    {
        create(firstname, lastname);
        jtf3.setForeground(Color.black);
        jtf2.setForeground(Color.black);

        id = Integer.toString(e.length); 
        current = Integer.parseInt(id);

        jta.setText("Employee #" + id + " " + firstname + " " + lastname + " was created.");
    }
}