Swing Lab 1

1. Create a new java project in Intellij. File → New → Project. You should see the following dialog. Click next.

2. Select Create project from template and click next.

3.  In the Project name field, type SwingIntro and click finish.

4. Extend the Main class with JFrame class. Ensure that you import javax.swing.*;

public class Main extends JFrame {

5. Modify the main method as shown below:

public static void main(String[] args) {

   java.awt.EventQueue.invokeLater(new Runnable() {

       @Override

       public void run() {

           new Main();

       }

   });

}

6. In the Main class constructor add the following coding

                  setVisible(true);

7. Run the program. You should be able to see the following window.

8. We have not added any component yet, but you can maximise, minimise. resize and close the window.
9. Close the window. Notice that even after closing the window, the application is still running. Let’s fix this by adding the following coding in the Main class constructor and run the application again.

setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

10. Let’s add a title to our frame and set the width and height of the frame using the following code to the Main class constructor and run the program.

setTitle("My first swing app");

setSize(500,300);

11. We have a frame, now let's add a canvas. We will use a Panel object as canvas and set the background color as blue. Then add the panel to frame. You will have to create an attribute called panel of type JPanel. Run the program.

panel  = new JPanel();

panel.setBackground(Color.BLUE);

add(panel);

12. Now that we have a panel, let’s add some component to the panel. Let's start by creating a button and adding it to the panel. Add the following code and run the program.

btn1 = new JButton();

btn1.setText("Click Me");

panel.add(btn1);

13. Notice that nothing happens when you click on the button. We need a listener to listen and respond to the events related to the button. To add a mouse listener add the following code to the constructor.

btn1.addMouseListener(new java.awt.event.MouseAdapter() {

   @Override

   public void mouseClicked(java.awt.event.MouseEvent ae){

       btn1MouseClicked(ae);

   }

});

14. Above codes adds a new instance of MouseAdapter as the listener. mouseClicked method is overridden to call the method that would run when the mouse is clicked.
15. Add a method called btn1MouseClicked to Main class. This method will print “Hello World!” to console. Run the application. The application should now print “Hello World!” to the console, every time you click “click me” button.
16. Now let’s add more components the panel. Add a JLabel to the panel. Set the text of the label to “test”. Run the program.
17. Modify the btn1.MouseClicked() to set the text of the label to “Hello World!” whenever the button is clicked.
18. Code a java swing project to create a simplified calculator the can be used for addition. The calculator will have a label, textfield and a button as shown below:

5.0 Add