Question

Write Java code which will create a GUI window on screen. The window has one button: Doggy. When the user selects Doggy, “Bow Bow” should be printed on screen. Justify your syntax.

Answer 1

Using ActionListner, string will be printed.

On button click value of i variable will be changed and based on i variable string will be displayed.

import java.awt.*;
import java.awt.event.*;

class Main extends Frame implements ActionListener
{
        //on button clock i var will changed
        int i=0;
        //string to print on screen
        String s="Bow Bow";
        //button declaration
        Button d;
        public static void main(String[] args)
        {       
            //craetes object of class
                new Main("Doggy Button");
        }

        public Main(String title)
        {
                //sets title, size of a dialog
                super(title);
                setSize(300,400);
                setVisible(true);

                d = new Button("Doggy"); // new Button doggy

                /*Default layer of frame is border layout so add in south*/
                add("South",d);
                
                //when action is performed, this event will be called
                d.addActionListener(this);

                //To close the window with close button
                //windowadapter
                addWindowListener(new WindowAdapter()
                {
                        //handling close button of dialog
                        public void windowClosing(WindowEvent e)
                        {
                                System.exit(0);
                        }
                });
        }

        public void actionPerformed(ActionEvent e)
        {
                //If button got presssed then print the string by matching button name
                String str = e.getActionCommand();
                if(e.getSource() instanceof Button)
                    //if "Doggy" button is clicked, string will be printed and i var will change
                        if(str.equals("Doggy"))
                        {
                                //To print the string call repaint() method
                                i=1;
                                repaint();
                        }
        }

    //to display string on the screen on i variable
        public void paint(Graphics g)
        {
                //Print the string
                if(i==1)
                    g.drawString(s,125,200);
        }
}

Please refer below ss for output

Outputs:

GUI display

When button is clicked