Why local variables are not allowed to use within the inner classes when it is allowed for others

Question

I know that local variables are not allowed to use within the inner classes. It must be a instance variable or a final one. Someone has said that it is because of the inner class object may exist out of the scope of method.

But I want to know why it is only for InnerClasses. When it is allowed for others. Basically I want to know why Approach 2 is allowed when Approach 1 is not.

Approach 1 :

MainGUI class

private void initializeGUI(){

    JTextArea rqJTextArea = new JTextArea();
    JTextArea rsJTextArea = new JTextArea();

    JButton button = new JButton("Ok"); // http://www.javaprogrammingforums.com/java-swing-tutorials/278-how-add-actionlistener-jbutton-swing.html

    button.addActionListener(new ActionListener() {

        public void actionPerformed(ActionEvent e){
            rsJTextArea.setText(rsJTextArea.getText() + "\n" + rqJTextArea.getText()); // Cannot refer to a non-final variable rsJTextArea inside an inner class defined in a different method
        }
    }); 

}

Approach 2 :

MainGUI class

private void initializeGUI(){

    JTextArea rqJTextArea = new JTextArea();
    JTextArea rsJTextArea = new JTextArea();

    JButton button = new JButton("Ok");

    SendActionListner sendActionListner = new SendActionListner();
    sendActionListner.setRqJTextArea(rqJTextArea);
    sendActionListner.setRsJTextArea(rsJTextArea);

    button.addActionListener(sendActionListner);   
}

SendActionListner class

public class SendActionListner implements ActionListener {

    public void actionPerformed(ActionEvent e) {

        rsJTextArea.setText(rsJTextArea.getText() + "\n" + rqJTextArea.getText());

    }


    public JTextArea getRqJTextArea() {
        return rqJTextArea;
    }
    public void setRqJTextArea(JTextArea rqJTextArea) {
        this.rqJTextArea = rqJTextArea;
    }
    public JTextArea getRsJTextArea() {
        return rsJTextArea;
    }
    public void setRsJTextArea(JTextArea rsJTextArea) {
        this.rsJTextArea = rsJTextArea;
    }


    JTextArea rqJTextArea = null;
    JTextArea rsJTextArea = null;

}