Java Program to Change the Background Color of the Frame on Clicking the Respective Color Buttons
Overview
In this blog, we will learn how to change a frame’s background color when its respective color buttons are clicked using the concept of Swing in Java programming language.
Program Description
The aim of this program is to change the background color of the frame whenever the user clicks the respective color buttons. For example, consider the frame given below; if the button “blue” is clicked, the background color of the frame should change from black to blue.
How Will the Output Look Like?
What is Swing?
Swing provides a set of classes that provides more powerful and flexible GUI components than does the AWT. Since they are light weight components, they provide a dynamic look and feel.
A swing GUI consists of two key items: components and containers.
Components:
A component is an independent visual control, such as a push button or slider.
All of Swing’s components are represented by classes defined within the package “javax.swing”.
Some of the swing components are: JButton, JLabel, JList, JRadioButton, etc.
In general, Swing components are derived from the “JComponent” class.
Containers:
A container holds a group of components.
The top-level swing containers are: JFrame, JApplet, JWindow and JDialog.
These containers do not inherit “JComponent” class.
Source Code
Here is the complete source code for the Java program that changes the background color of the frame on clicking the respective color buttons. Check out the code explanation which is given below for clear understanding of the program.
Program Explanation
JFrame frame = new JFrame("Colourful window");
JButton red = new JButton("RED");JFrame class is used to create a new JFrame container with the given text as the frame’s title.
JButton class is used to create button with the given text as content of the button.
Color c = new Color(255, 255, 255);
Font font = new Font("Lucida Calligraphy", Font.BOLD, 9);red.setBounds(40, 100, 100, 40);
red.setBackground(c);
red.setFont(font);
Color class with RGB values as parameters, is used to set color to the component.
Font class is used to set font for the GUI component. It has font name, font style and font size as its parameters.
The setBounds() method is used for the button to specify the position and size of the button. Its syntax is setBounds(x, y, width, height).
The setBackground() method is used to set background color to the button.
Also, the setFont() method is used to set font to the button.
frame.add(red);
red.addActionListener(this);The add() method is used to add the button to the frame.
The ActionListener interface(with actionPerformed() as an interface method) is called when the button is clicked.
frame.getContentPane().setBackground(Color.black);
frame.setLayout(null);
frame.setSize(650, 600);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);The getContentPane() method retrieves the content pane layer so that you can add an object to it.
The setLayout() method is used to set a layout to the frame.
The setSize() method sets the width and height of the frame.
The setVisible() makes the frame appear on the screen.
Calling setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE), the frame will be closed.Program Explanation
public void actionPerformed(ActionEvent ae)
{
if(ae.getSource() == red)
frame.getContentPane().setBackground(Color.RED);
}The actionPerfomed() method is invoked automatically when you click on a button.
The getSource() method is used to determine which button was clicked. If the clicked button is red, then the frame’s background color is changed to red color.
Similarly, the other buttons are designed and functioned in the mentioned manner.
Program Output
The output frame is displayed for the program when the pink button is clicked.
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