Background color change help

[Rebecca Weber]

Writing a guessing game program. The user is to guess a number between 1 - 1000. Every time the user guesses too low, the background color of the JFrame is to change to blue, if the user guesses too high, it changes to red. I cannot get the background color to change at all. Everything else seems to running ok with the program. Any help would be appreciated. Thanks. Here is my code:

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JTextField;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.FlowLayout;
import java.awt.Color;
import java.awt.Graphics;

public class Guess extends JPanel 
{

	//declare variables and components
	private int number, guessCount;
	private int lastDistance;
	private static JTextField guessInput;
	private static JLabel prompt1;
	private static JLabel prompt2, userPrompt;
	private static JButton newGame;
	private Color background;

	public static void main(String args[]) 
	{
		JFrame frame = new JFrame("Guess the Number");
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		
		Guess myPanel = new Guess(); 			//create myPanel
		myPanel.setBackground(Color.white);		//set background color to white
		frame.add( myPanel ); 					//add myPanel to frame
		frame.setSize( 500, 500 ); 					//set frame size
		frame.setVisible( true ); 					//display frame
		
		frame.setLayout(new FlowLayout());
		frame.add(prompt1);
		frame.add(prompt2);
		frame.add(guessInput);
		frame.add(userPrompt);
		frame.add(newGame);
	}

	// set up GUI and initialize values
	public Guess() 
	{
		//title the frame
		super();

		//default values
		//guessCount = 0;
		background = Color.WHITE;

		// create GUI components
		prompt1 = new JLabel("I have a number between 1 and 1000. Can you guess my number?");
		prompt2 = new JLabel("Please enter your first guess:");
		guessInput = new JTextField(5);
		guessInput.addActionListener(new GuessHandler());
		userPrompt = new JLabel();
		
		//button starts a new game and generates a new random number.
		//the JTextField is again changed to editable
		newGame = new JButton("New Game");

		//action listener will respond to events
		newGame.addActionListener(new ActionListener() 
		{
			public void actionPerformed(ActionEvent e) 
			{
				
				//reset the label prompting the user to guess
				//userPrompt.setText("Guess Result");
				
				//clear text field
				guessInput.setText("");
				
				//allow user input again
				guessInput.setEditable(true);
				
				//return to default color
				background = Color.WHITE;
				theGame();
				//repaint();
			}
		});

		//start the game
		theGame();
	}

	//method to choose a new random number and reset default guess
	public void theGame() 
	{
		//random between 1 and 1000
		number = (int) (Math.random() * 1000 + 1);
		//guessCount = 0;
	}

	//change background color. use a variable to store background
	//so that we can change it according to the user input
	public void paintComponent(Graphics g) 
	{
		super.paintComponents(g);
		this.setBackground(background);
	}

	//method to react to new guess
	public void react(int guess) 
	{
		//increment gueesCount to 1 and set distance to 1000
		guessCount = 0;
		int currentDistance = 1000;

		//first guess will not change the background color because we
		//do not have a second guess to compare with yet
		if (guessCount == 1) 
		{

			//absolute value of user input minus actual number
			lastDistance = Math.abs(guess - number);
			
			//display text
			if (guess > number)
				userPrompt.setText("Too High");
			else
				userPrompt.setText("Too Low");

			//if guess count is greater than 1 we can compare guesses
		} else 
		{
			//take the difference between user input and actual number
			currentDistance = Math.abs(guess - number);
			
			//guess is too high
			if (guess > number) 
			{
				//set display text
				userPrompt.setText("Too High");
				
                                //set background color
				background = (currentDistance <= lastDistance) ? Color.red : Color.blue;
				
				//set this guess to the currentDistance for next comparison
				lastDistance = currentDistance;
			}
			//guess is too low
			else if (guess < number) 
			{
				//set display text
				userPrompt.setText("Too Low.");
				
				//set background color
				background = (currentDistance <= lastDistance) ? Color.red : Color.blue;
				
				//set this guess to the currentDistance for next comparison
				lastDistance = currentDistance;
			}
			
			//guess is correct
			else 
			{
			    //if the user gets the right number, display Correct!
				userPrompt.setText("Correct!");
				
				//make the text box uneditable so there are no future guesses
				//without starting a new game
				guessInput.setEditable(false);
			}
			//repaints this component. 
			repaint();
		}
	} // end method react

	// inner class acts on user input
	class GuessHandler implements ActionListener 
	{
		public void actionPerformed(ActionEvent e) 
		{
			//parse input from stirng to int for comparison
			int guess = Integer.parseInt(guessInput.getText());
			//call react method and send parameter  
			react(guess);
			//select text in inputbox
			guessInput.selectAll();
		}
	}
}

[Darryl Burke]

Change the background of the JFrame's contentPane instead. To understand why, read the API for JRootPane.

[Rob Spoor]

Don't call setBackground from paintComponent. That will trigger another repaint which will call paintComponent again. Instead of using your variable "background" just call setBackground in your event handlers.

And you're calling super.paintComponents instead of super.paintComponent. Because both methods exist you didn't get a compiler error but you should definitely fix that.