Java Swing - JPanel With Examples

Last Updated : 10 Nov, 2021

JPanel, a part of the Java Swing package, is a container that can store a group of components. The main task of JPanel is to organize components, various layouts can be set in JPanel which provide better organization of components, however, it does not have a title bar.

Constructors of JPanel

JPanel(): creates a new panel with a flow layout
JPanel(LayoutManager l): creates a new JPanel with specified layoutManager
JPanel(boolean isDoubleBuffered): creates a new JPanel with a specified buffering strategy
JPanel(LayoutManager l, boolean isDoubleBuffered): creates a new JPanel with specified layoutManager and a specified buffering strategy

Commonly used Functions of JPanel

add(Component c): Adds a component to a specified container
setLayout(LayoutManager l): sets the layout of the container to the specified layout manager
updateUI(): resets the UI property with a value from the current look and feel.
setUI(PanelUI ui): sets the look and feel of an object that renders this component.
getUI(): returns the look and feel object that renders this component.
paramString(): returns a string representation of this JPanel.
getUIClassID(): returns the name of the Look and feel class that renders this component.
getAccessibleContext(): gets the AccessibleContext associated with this JPanel.

Let us take a sample program in order to illustrate the use of JPanel class by appending sequential execution snapshots of outputs justifying the below program sets as follows:

Example:

Java

// Java Program to Create a Simple JPanel
// and Adding Components to it

// Importing required classes
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

// Class 1
// Helper class extending JFrame class
class solution extends JFrame {

    // JFrame
    static JFrame f;

    // JButton
    static JButton b, b1, b2;

    // Label to display text
    static JLabel l;

    // Main class
    public static void main(String[] args)
    {
        // Creating a new frame to store text field and
        // button
        f = new JFrame("panel");

        // Creating a label to display text
        l = new JLabel("panel label");

        // Creating a new buttons
        b = new JButton("button1");
        b1 = new JButton("button2");
        b2 = new JButton("button3");

        // Creating a panel to add buttons
        JPanel p = new JPanel();

        // Adding buttons and textfield to panel
        // using add() method
        p.add(b);
        p.add(b1);
        p.add(b2);
        p.add(l);

        // setbackground of panel
        p.setBackground(Color.red);

        // Adding panel to frame
        f.add(p);

        // Setting the size of frame
        f.setSize(300, 300);

        f.show();
    }
}

Output:

Example 2:

Java

// Java Program to Create a JPanel with a Border Layout
// and Adding Components to It

// Importing required classes
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

// Main class
// Extending JFrame class
class solution extends JFrame {

    // JFrame
    static JFrame f;

    // JButton
    static JButton b, b1, b2, b3;

    // Label to display text
    static JLabel l;

    // Main driver method
    public static void main(String[] args)
    {
        // Creating a new frame to store text field and
        // button
        f = new JFrame("panel");

        // Creating a label to display text
        l = new JLabel("panel label");

        // Creating a new buttons
        b = new JButton("button1");
        b1 = new JButton("button2");
        b2 = new JButton("button3");
        b3 = new JButton("button4");

        // Creating a panel to add buttons
        // and a specific layout
        JPanel p = new JPanel(new BorderLayout());

        // Adding buttons and textfield to panel
        // using add() method
        p.add(b, BorderLayout.NORTH);
        p.add(b1, BorderLayout.SOUTH);
        p.add(b2, BorderLayout.EAST);
        p.add(b3, BorderLayout.WEST);
        p.add(l, BorderLayout.CENTER);

        // setbackground of panel
        p.setBackground(Color.red);

        // Adding panel to frame
        f.add(p);

        // Setting the size of frame
        f.setSize(300, 300);

        f.show();
    }
}

Output:

Example 3:

Java

// Java Program to Create a JPanel with a Box layout
// and Adding components to it

// Importing required classes
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

// Main class
// Extending JFrame class
class solution extends JFrame {

    // JFrame
    static JFrame f;

    // JButton
    static JButton b, b1, b2, b3;

    // Label to display text
    static JLabel l;

    // Main drive method
    public static void main(String[] args)
    {
        // Creating a new frame to store text field and
        // button
        f = new JFrame("panel");

        // Creating a label to display text
        l = new JLabel("panel label");

        // Creating a new buttons
        b = new JButton("button1");
        b1 = new JButton("button2");
        b2 = new JButton("button3");
        b3 = new JButton("button4");

        // Creating a panel to add buttons and
        // textfield and a layout
        JPanel p = new JPanel();

        // Setting box layout
        p.setLayout(new BoxLayout(p, BoxLayout.Y_AXIS));

        // Adding buttons and textfield to panel
        p.add(b);
        p.add(b1);
        p.add(b2);
        p.add(b3);
        p.add(l);

        // Setting background of panel
        p.setBackground(Color.red);

        // Adding panel to frame
        f.add(p);

        // Setting the size of frame
        f.setSize(300, 300);

        f.show();
    }
}

Output:

Henceforth, we are successfully able to generate buttons in our panel.

Note: In the previous Program, border layout and Box Layout are used. Different other layouts can be used to organize the components in a definite pattern, such as card layout, grid layout, etc.