CODEWITHSUNDEEP
javaarraysconstructor2d
CuriousFellow
CuriousFellow

Reputation: 215

Instantiating a 2d array in a java constructor?

I am so confused. I need to make a constructor to create a 2d array with parameters called from main method.. Every time I call the Seats 2D array in another method of the same class, I get an error. Why is that and how do I use the array I made in the constructor?

class MovieSeating 
{

public MovieSeating(int rowNum, int columnNum)
{
    String [][] Seats = new String[rowNum][columnNum];
    for (int r = 0; r < rowNum; r++)
    {
        for (int c = 0; c < columnNum; c++)
        {
            Seats[r][c] = "???";
        }
    }
}

private Customer getCustomerAt(int row, int col)
{
    System.out.println("Customer at row " + row + " and col " + col + "." );
    System.out.println(Seats[row][col]);

}

Upvotes: 3

Views: 35739

Answers (5)

Chandu D
Chandu D

Reputation: 501

Here i am sending code snipped i hope this will help u

public Charts(int graph_min, int graph_max, double[] dataset, int stepSize,double[][] percentRange) {

//here double[][]={{10},{100}};
		this(graph_min,graph_max,dataset);
		this.stepSize = stepSize;
		
		System.out.println("double constructor    "+percentRange.length);
		this.percentRange = new double[percentRange.length][percentRange[0].length];
		System.out.println("percentRange: "+this.percentRange);
		 for (int i = 0; i < percentRange.length; i++) {
			
	        for (int j = 0; j < percentRange[i].length; j++) {
	            	this.percentRange[i][j] = percentRange[i][j];
	            	 System.out.println("ps_Axis constructor valuesd  "+this.percentRange[i][j]);
	           }
	       
	}

Upvotes: 0

Nishant Lakhara
Nishant Lakhara

Reputation: 2445

Declare the array outside the constructor as a private variable :

class MovieSeating 
{
    private String [][] Seats;
public MovieSeating(int rowNum, int columnNum)
{
    Seats = new String[rowNum][columnNum];
    for (int r = 0; r < rowNum; r++)
    {
        for (int c = 0; c < columnNum; c++)
        {
            Seats[r][c] = "???";
        }
    }
}

private void getCustomerAt(int row, int col)
{
    System.out.println("Customer at row " + row + " and col " + col + "." );
    System.out.println(Seats[row][col]);

}
}

Upvotes: 1

Narendra Pathai
Narendra Pathai

Reputation: 41935

class MovieSeating{

private String[][] seats;

public MovieSeating(int col, int row){
  seats = new String[row][col];
}
}

Make seats an instance variable to increase the scope of it.

Upvotes: 0

user987339
user987339

Reputation: 10707

You are on a good track, but you have to make Seats instance variable in order to get proper results:

private String [][] Seats;
public MovieSeating(int rowNum, int columnNum)
{
    Seats = new String[rowNum][columnNum];
    for (int r = 0; r < rowNum; r++)
    {
        for (int c = 0; c < columnNum; c++)
        {
            Seats[r][c] = "???";
        }
    }
}

Upvotes: 3

Maroun
Maroun

Reputation: 95948

Seats is not known in the main, it's known only in the scope of the constructor.

You should make it a class member and initialize it in the constructor:

class MovieSeating  {
   private String [][] Seats;
   ..
   public MovieSeating(int rowNum, int columnNum) {
      Seats = new String[rowNum][columnNum];
      ..
   }
}

Upvotes: 0

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