Colors actionListener

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class Colors extends JFrame
        //1. add ActionListener
        implements ActionListener{
    //UUIs for buttons & textfield
    private JButton btnred, btnblue;
    private JTextField txt1;
    private Container pane = getContentPane();

    public Colors(){

        pane.setBackground(Color.white);
        pane.setLayout(new FlowLayout());

        //create UI's object
        btnred = new JButton("Red");
        btnred.addActionListener(this);
        //2. Add listener to UI button
        btnblue = new JButton("Blue");
        btnblue.addActionListener(this);
        txt1=new JTextField("Color string");

        //UI placement
        pane.add(btnred);
        pane.add(btnblue);
        pane.add(txt1);
    }

    //3. add actionPerformed method
    public void actionPerformed(ActionEvent e){
        Object ui = e.getSource();
        if (ui==btnred){
            pane.setBackground(Color.red);
            txt1.setText("Red");
        }
        else if (ui==btnblue){
            pane.setBackground(Color.blue);
            txt1.setText("Blue");

        }
    }

    public static void main(String[] args) {
        // TODO Auto-generated method stub

        Colors frame = new Colors();
        frame.setDefaultCloseOperation(
                JFrame.EXIT_ON_CLOSE);
        frame.setTitle("Colors Test");
        frame.setSize(300, 200);
        frame.setVisible(true);
    }
}