Question

Write an application that plays "guess the number" as follows: Your application chooses the number to be guessed by selecting an integer at random in the range \(1-1000 .\) The application then displays the following in a label: I have a number between 1 and 1000 . Can you guess my number? Please enter your first guess. A JTextField should be used to input the guess. As each guess is input, the background color should change to either red or blue. Red indicates that the user is getting "warmer," and blue indicates that the user is getting "colder." A JLabel should display either "Too High" or "Too Low" to help the user zero in on the correct answer. When the user gets the correct answer, "Correct!" should be displayed, and the JTextField used for input should be changed to be uneditable. A JButton should be provided to allow the user to play the game again. When the JButton is clicked, a new random number should be generated and the input JTextField changed to be editable.

Short answer

Create a random number, set up a UI, handle guesses with feedback, and allow a restart.

Step-by-step solution

Generate a Random Number

First, implement the functionality to generate a random integer between 1 and 1000 using Java's Random class. This number will be the target number the user needs to guess. For example, initialize with `Random random = new Random();` and select a number using `int numberToGuess = random.nextInt(1000) + 1;`.

Create the User Interface

Set up the user interface components: a JLabel to display instructions and results, a JTextField to accept user input for guesses, and a JButton to reset and play again. Layout these components using a suitable LayoutManager, like BorderLayout.

Implement the Guess Submission

Add an ActionListener to the JTextField so that when the user presses enter, the input is submitted. Parse the input from the JTextField into an integer and compare it with the target number `numberToGuess`.

Compare and Respond

Use conditional statements to compare the guessed number to `numberToGuess`. If the guess is higher, display 'Too High' and check if the guess is closer than the previous one to change the color to red, else to blue. If it's lower, display 'Too Low' with the same color logic.

Handle Correct Guess

When the user guesses correctly, set the JLabel to "Correct!", make the JTextField non-editable, and change its background color to signify victory.

Add Restart Functionality

Implement an ActionListener for the JButton that resets the game. It should generate a new random number, clear the JTextField, set it back to editable, and clear any result shown in the JLabel.

Key concepts

Random Number Generation

In Java, generating random numbers is crucial for applications like the "Guess the Number" game. Java provides a straightforward way to generate random numbers using the `Random` class from `java.util` package. This enables developers to create engaging and unpredictable user experiences.

To generate a random number, first, instantiate the `Random` class: ```java Random random = new Random(); ``` This object can generate random integers, with the method `nextInt(int bound)`, which produces a number from 0 (inclusive) to the specified bound (exclusive). For example, `random.nextInt(1000) + 1;` will yield a number between 1 and 1000. Adding the `1` ensures the range includes both 1 as the lower bound and 1000 as the upper bound.

Random number generation is useful in scenarios where unpredictability is desired in your program's behavior.

User Interface Design

Creating a user-friendly interface is key in application development, particularly in interactive programs like the "Guess the Number" game. In Java, the Swing library offers a wide array of components to create robust and engaging graphical user interfaces (GUIs).

For this exercise, components such as `JLabel`, `JTextField`, and `JButton` help in interacting with the user. A `JLabel` can display static text to guide the user, like showing instructions or feedback ("Too High," "Too Low," "Correct!").

The `JTextField` allows the user to input guesses. It's a simple but powerful component that captures user input effectively. When creating these components, consider the layout manager to organize them efficiently. A `BorderLayout` can be used to arrange your components systematically across the window.

When designing the user interface, ensure that it is intuitive. Users should easily understand how and where to make their input and get feedback.

Event Handling

Event handling in Java allows programs to be interactive by responding to user inputs or system-generated events. Also known as event-driven programming, it enables the application to act on actions like clicks, keystrokes, or changes within the GUI.

In the "Guess the Number" game, event handling is integral. For instance, the `ActionListener` interface can listen for actions performed on `JButton` and `JTextField`. For the `JTextField`, the listener captures the event when the user presses 'Enter'. This event submits the guess, allowing the program to process the input immediately.
Additionally, the `JButton` uses an ActionListener to trigger a new game session. Once the button is clicked, the program resets the game state by generating a new random number and resetting the input field. This kind of flexibility is crucial to maintain a dynamic and responsive user interface.

Conditional Statements

Conditional statements in Java allow the execution of specific code blocks based on certain conditions. These are fundamental in controlling the flow of a program.

For the "Guess the Number" game, conditional statements such as `if`, `else if`, and `else`, are used to compare the user's guess against the target number. - **Too High or Too Low**: When a user submits their guess, the program checks: ```java if(guess > numberToGuess) { // Display "Too High" } else if(guess < numberToGuess) { // Display "Too Low" } ``` The application provides feedback to help guide the player's next guess.

- **Correct Guess**: Check for correctness with: ```java if(guess == numberToGuess) { // Display "Correct!" and disable input } ``` This signals to the player that the game is won, and typically, further inputs are disabled.

Conditional logic also drives the "warmer" or "colder" feedback by comparing the current guess's proximity to the target compared to previous guesses. These decisions enhance the interactivity and challenge of the game.