자바 this에 관해 질문드립니다

package lib2;

import java.awt.*;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import javax.swing.*;

class MyFrame2 extends JFrame{

public MyFrame2() {

super("Listener입니다.");

setDefaultCloseOperation(JFrame.EXITONCLOSE);

Container conpane=getContentPane();

conpane.setBackground(Color.ORANGE);

conpane.setLayout(new FlowLayout());

JButton bb=new JButton("Hello");

bb.addActionListener(new MyActionLis());

setSize(300,300);

setVisible(true);//프레임보여줌

conpane.add(new JButton("Click"));

conpane.add(new JButton("OK"));

conpane.add(new JButton("Cancel"));

conpane.add(bb);

}

private class MyActionLis implements ActionListener{

public void actionPerformed(ActionEvent e) {

JButton b=(JButton)e.getSource();

if(b.getText()=="1")

b.setText("3");

else

b.setText("1");

• MyFrame2.this.setTitle(b.getText());

}

}

}

public class myFrame {

public static void main(String[] args) {

MyFrame2 frame=new MyFrame2();

;

}

}

이부분에서 this를 굳이 써야하는 이유가 있을까요..??

MyFrame2.setTitle(b.getText())와 다른점을 도저히 모르겠습니다