CODEWITHSUNDEEP
javaprintingmultidimensional-arrayarrays
Dillinger J
Dillinger J

Reputation: 1

Printing a 2d character array

Printing out a 2d character array is not difficult, but the way I need to do it seems to be.

My current goal is initialize a 2d character array, such that every cell contains '-'. This must be done within the constructor method. Below is what I have thus far.

public class GameOfLife {

public final int MAX_SIZE = 12;

// instance variables
private char [][] current = new char[MAX_SIZE][MAX_SIZE];
private char [][] next    = new char[MAX_SIZE][MAX_SIZE];
Scanner keyboard = new Scanner(System.in);

  /**
   * Constructor for objects of class GameOfLife.  
   * Initializes the current array to '-'.
   */

    public void GameOfLife() {
        for ( int i = 0; i < MAX_SIZE; i++){
            for ( int j = 0; j < MAX_SIZE; j++){
                current [i][j] = '-';
            }
        }

        @Override public String toString() {
        StringBuilder sb = new StringBuilder();

        for ( int i = 0; i < MAX_SIZE; i++){
            for ( int j = 0; j < MAX_SIZE; j++){
                sb.append(current[i][j]);
                sb.append(" ");
            }
            sb.append("\n"); // add new line
        } 

        return sb.toString(); // convert to String and return
      }
    }`

I know how to properly print it if it were just to be printed within this method; however, I must use the "GameOfLife" constructor in the following way. This next code is in the driver class, which is called "gameoflifedriver".

   // Create a GameOfLife object
    GameOfLife lifeGame = new GameOfLife();
    System.out.print(lifeGame);

The problem that I am having is that the lifeGame will not print, and an odd error message occurs - GameOfLife@5d3892b3. I know there are ways to print it, but I cannot change any of the code in the driver class - so all of the edits must be in the GameOfLife code. Any thoughts?

Upvotes: 0

Views: 92

Answers (2)

Christian Tapia
Christian Tapia

Reputation: 34146

You can override the toString() method. Also you could use a StringBuilder:

@Override
public String toString() {
    StringBuilder sb = new StringBuilder();

    for ( int i = 0; i < MAX_SIZE; i++){
        for ( int j = 0; j < MAX_SIZE; j++){
            sb.append(current[i][j]);
            sb.append(" ");
        }
        sb.append("\n"); // add new line
    } 

    return sb.toString(); // convert to String and return
}

Then you can print this representation with:

GameOfLife lifeGame = new GameOfLife();
System.out.print(lifeGame);

Note: Constructors don't have a return type, so you shouldn't declare it with return type void:

public GameOfLife() {/* Constructor body */}

Upvotes: 2

ravi.patel
ravi.patel

Reputation: 119

The Class GameOfLife constructor should not have void return type (java rule). And the toString() method is good to implement.

Upvotes: 0

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