Java Swing | Popup and PopupFactory with examples

Popup and PopupFactory are a part of the Java Swing library. Popups are used when we want to display to the user a Component on the top of all the other Components in that particular containment hierarchy. PopupFactory is the class that is used to create popups. Popups have a very small life cycle, and generally are lightweight components having limited sub-components.
Constructor for the class are :

1. PopupFactory(): creates an object for popup factory

Commonly used methods: 

method	explanation
getPopup(Component o, Component c, int x, int y)	Creates a Popup for the Component o containing the Component c at a location x, y on the owner component.
hide()	Hides and disposes of the Popup.
show()	Makes the Popup visible.

Below programs will illustrate the use of a popup: 

1. Java Program to create a popup and display it on a parent frame: We create a popup p by creating a popup factory and using the function getpopup() which returns a popup. We add this popup to a frame f titled “pop” we will create a label and add t to a container panel p2 and set the background of panel p2 using setBackground() function. We will add the container panel p2 to the popup. We will also create a button b titled “click” added with an action listener and displays the popup when the button is pressed. The button b is added to a panel and the panel is added to the frame. Frame is set to the size 400,400 using setSize(400,400). Finally, the frame is displayed using show() function. 
   

Java

// Java Program to create a popup and display
// it on a parent frame
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
class pop extends JFrame implements ActionListener {
    // popup
    Popup p;

    // constructor
    pop()
    {
        // create a frame
        JFrame f = new JFrame("pop");

        // create a label
        JLabel l = new JLabel("This is a popup");

        f.setSize(400, 400);

        PopupFactory pf = new PopupFactory();

        // create a panel
        JPanel p2 = new JPanel();

        // set Background of panel
        p2.setBackground(Color.red);

        p2.add(l);

        // create a popup
        p = pf.getPopup(f, p2, 180, 100);

        // create a button
        JButton b = new JButton("click");

        // add action listener
        b.addActionListener(this);

        // create a panel
        JPanel p1 = new JPanel();

        p1.add(b);
        f.add(p1);
        f.show();
    }

    // if the button is pressed
    public void actionPerformed(ActionEvent e)
    {
        p.show();
    }
    // main class
    public static void main(String args[])
    {
        pop p = new pop();
    }
}

1. Output: 
   

1. Java Program to create a popup (add a panel) and display it on a parent frame and also add an action listener to the popup: We create a popup p by creating a popup factory and using the function getpopup() which returns a popup. We will set the look and feel to System look and feel. We add this popup to a frame f titled “pop”, we will create a label and a button b19 titled “OK”( we will set the font of the label to a specified font object) and add it to a container panel p2 and set the background of panel p2 using setBackground() function. We will add the container panel p2 to the popup. We will also create a button b titled “click” added with an action listener and displays the popup when the button is pressed. The button b is added to a panel and the panel is added to the frame. Frame is set to the size 400,400 using setSize(400,400). finally, the frame is displayed using show() function. 
   

Java

// Java Program to create a popup (add a panel) and
// display it on a parent frame and also
// add action listener to the popup
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
class pop1 extends JFrame implements ActionListener {
    // popup
    Popup po;

    // frame
    JFrame f;

    // panel
    JPanel p;

    // popupfactory
    PopupFactory pf;

    // constructor
    pop1()
    {
        // create a frame
        f = new JFrame("pop");

        f.setSize(400, 400);

        pf = new PopupFactory();

        // create a label
        JLabel l = new JLabel("This  is a popup menu");

        // create a new button
        JButton b19 = new JButton("OK");

        // add action listener
        b19.addActionListener(this);

        try {
            // set windows look and feel
            UIManager.setLookAndFeel(UIManager.
                  getSystemLookAndFeelClassName());
        }
        catch (Exception e) {
        }

        // create a panel
        p = new JPanel();

        p.setBackground(Color.blue);

        // create a font
        Font fo = new Font("BOLD", 1, 14);

        l.setFont(fo);

        // add contents to panel
        p.add(l);
        p.add(b19);

        p.setLayout(new GridLayout(2, 1));

        // create a popup
        po = pf.getPopup(f, p, 180, 100);

        // create a button
        JButton b = new JButton("click");

        // add action listener
        b.addActionListener(this);

        // create a panel
        JPanel p1 = new JPanel();

        p1.add(b);
        f.add(p1);
        f.show();
    }

    // if the button is pressed
    public void actionPerformed(ActionEvent e)
    {
        String d = e.getActionCommand();
        // if ok button is pressed hide the popup
        if (d.equals("OK")) {
            po.hide();

            // create a popup
            po = pf.getPopup(f, p, 180, 100);
        }
        else
            po.show();
    }
    // main class
    public static void main(String args[])
    {
        pop1 p = new pop1();
    }
}

1. Output: 
   

• https://docs.oracle.com/javase/7/docs/api/javax/swing/Popup.html
• https://docs.oracle.com/javase/7/docs/api/javax/swing/PopupFactory.html