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Java Active Learning WorkBook: Scaffolded Programming Activities Beyond The Basics.

Celine Latulipe, Devon Blewett, Lara De Leon

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Section 13.3 Stretch Level

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Multidimensional Arrays
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Subsection 13.3.1 Overview

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Note 13.3.1.

Since Runestone Academy does not support the use of a Scanner in its environment, please use an alternative platform to complete this exercise! You may use replit.com, Visual Studio Code, or any other IDE of your choice that supports Java and allows the use of Scanner for user input.
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This is a basic grid-based game in Java where a player will move through a grid collecting coins, with the goal of reaching the exit. The player starts at the top left corner of the grid and the exit is at the bottom right corner. The player will move through the grid using the ’W’, ’A’, ’S’, and ’D’ keys.
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Here is an example of what the grid can look like:
P O . . . 
. . . . O 
. . . . . 
. . . . . 
. O . . E
  • The player is denoted by ’P’
  • The coins are denoted by ’O’
  • The exit is denoted by ’E’
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The player will move on the grid through user input, which will be handled by a Scanner. Each time the game is run, a new grid must be created. That is, the coins must be placed at a random spot each time.
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Subsection 13.3.2 Instructions

  1. Building the grid with char[][] buildGrid(int width, int height)
    • Create a grid of char[][] and populate it with ’.’ which represents empty spaces
  2. Printing the grid with printGrid(char[][] grid)
    • Iterate through the char[][] and print each row
  3. Placing coins on the grid with placeCoins(char[][] grid, int coinCount)
    • This method will place coins randomly on the grid
    • The number of coins to put on the grid is specified by the coinCount parameter. Coins are represented by ’O’
    • Hint.
      • Use a Random object to generate random x and y positions for the coins. Here is a code snippet that uses Random: 
        Random random = new Random();
int randomInt = random.nextInt(100);
        This will generate a random integer from 0 (inclusive) to 100 (exclusive)
  4. Implementing game logic in playGame(int width, int height, int coinCount)
    • Call the buildGrid() method and place the player (P) and the exit (E) in their designated spots on the grid. Ensure that you initialize variables to keep track of the player’s position
    • Populate the grid with coins using the placeCoins() method
    • Use a while loop to keep the game running until the player reaches the exit. Inside the loop, you will:
      • Print the grid after each move
      • Prompt the player to enter their next move and read the input in using a Scanner
      • Update the player’s position on the grid to the new coordinates and if they have moved to a coin, update their points
      • End the game once the player has reached the exit
      • Make sure to handle the case where the player tries to move out of bounds by checking if the new coordinates are within the valid range before updating the player’s position
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Here is an example of what the gameplay output may look like:
P . . 
O . . 
. . E 
Enter move (Only WASD, case sensitive): 
S
Got a coin!
. . . 
P . . 
. . E 
Enter move (Only WASD, case sensitive): 
D
. . . 
. P . 
. . E 
Enter move (Only WASD, case sensitive): 
D
. . . 
. . P 
. . E 
Enter move (Only WASD, case sensitive): 
S
You won! Points: 1
You have attempted 1 of 2 activities on this page.
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