GUI - Changing the color of the JFrame

Question

I'm new in Java and I need your help in implementing a GUI. Below is a Guessing Game code. It works.

  import javax.swing.*;
  import java.awt.*;
  import java.awt.event.ActionEvent;
  import java.awt.event.ActionListener;
  import java.util.Random;

  public class GuessGame extends JFrame {
     private JTextField guessTextField;
     private JLabel introLabel, guessLabel, clueLabel;
     private JButton enterB, playAgainB;

     private int randomNumber;

     public GuessGame() {
        super("Guessing Game!");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Creates components
        enterB = new JButton("Guess");
        playAgainB = new JButton("Quit");
        introLabel = new JLabel("I have a number between 1 and 1000.");
        guessLabel = new JLabel("Can you guess my number? Please enter your guess:");

        clueLabel = new JLabel("");
       // comment2 = new JLabel(" ");
        guessTextField = new JTextField(5);

        //content pane
        Container c = getContentPane();
        setLayout(new FlowLayout());

        //adding component to the pane
        c.add(introLabel);
        c.add(guessLabel);
        c.add(guessTextField);
        //c.add(comment2);
        c.add(enterB);
        c.add(playAgainB);
        c.add(clueLabel);

        //enterB.setMnemonic('G');
        //playAgainB.setMnemonic('Q');

        setSize(350, 200);
        setLocationRelativeTo(null);
        setVisible(true);
        //setResizable(false);

        initializeNumber();

        //creating the handler
        GuessButtonHandler ghandler = new GuessButtonHandler(); //instantiate new object
        enterB.addActionListener(ghandler); // add event listener

        QuitButtonHandler qhandler = new QuitButtonHandler();
        playAgainB.addActionListener(qhandler);
     }

     private void initializeNumber() {
        randomNumber = new Random().nextInt(1000) + 1;
        System.out.println(randomNumber);
     }

     class QuitButtonHandler implements ActionListener {
        public void actionPerformed(ActionEvent e) {
           System.exit(0);
        }
     }

     class GuessButtonHandler implements ActionListener {
        public void actionPerformed(ActionEvent e) {
           int getUserInput;
           int diff;
           int Difference;
           try {
              getUserInput = Integer.parseInt(guessTextField.getText().trim());      

              if (getUserInput == randomNumber) {
                  clueLabel.setText("                              Correct!");
              }
              if (getUserInput > randomNumber) {
                 clueLabel.setText("                           Too High");
              } else {
                 clueLabel.setText("                           Too Low");
              }


           } 
           catch (NumberFormatException e1) {
              clueLabel.setText("Enter a VALID number!");
           }
        }


     }



     public static void main(String args[]) {
        //instantiate gueesgame object
         GuessGame app = new GuessGame();

     }
  }

However, the color of the window should change into red or blue. Please help me with this code. I'm new in Java and it's syntax. I'd really appreciate your help. Thank you!

Answer 1

You could use:

current = Integer.parseInt(guessTextField.getText().trim()); 
if (!firstTime) {
    if (getUserInput > previous) {
        getContentPane().setBackground(Color.red);
    } else {
        getContentPane().setBackground(Color.blue);
    }
}

where firstTime and previous are class member variables.

Don't forget to assign previous if the getUserInput == randomNumber is not met.

Update:

You are setting the background blue twice:

if (getUserInput < randomNumber) {
   clueLabel.setText("Too Low");
   getContentPane().setBackground(Color.blue); <------ remove this extra call
   previous = getUserInput;
}

Answer 2

A code is better than thousand words.....

 if (current_Input > previous) {
    c.setBackground(Color.red);
 } else {
    c.setBackground(Color.blue);
 }