Create a two dimensional string array anArray[2][2]

Question

I'm currently on a self learning Java course and am completely stumped at one of my assignments, can anyone give me some pointers please? Bear in mind that I am completely new to Java so I need it to be as simple as.

The question: 3. Create a Java program called TwoDimArray and implement the following:

Create a two dimensional string array anArray[2][2].
Assign values to the 2d array containing any Country and associated colour. 

    Example:

    France Blue 

    Ireland Green 

Output the values of the 2d array using nested for loops.

The code I have come up with that is also not working:

public class TwoDimArray {
  public static void main(String[] args) {
    char Ireland = 0;
    char Green = 1;
    char England = 2;
    char White = 3;
    char firstArray[][] = {{Ireland},{Green}};
    char secondArray[][] = {{England},{White}};

    System.out.println();
    display(firstArray);
    System.out.println();
    display(secondArray);

  }

  public static void display(char a[][]) {
    for (char row = 0; row < a .length; row++) {
      for (char col = 0; col < a [row] .length; col++) {
        System.out.print(a[row][col] + " ");
      }

      System.out.println();
    }
  }
}

Can anyone give me some pointers? I can't seem to find anything that helps me on the web so thought I'd come here and ask. Thanks in advance.

"Create a two dimensional string array". Did you do that ? — Alexis C.
– Alexis C., Commented Dec 3, 2013 at 18:49
I have no idea how I missed that at all, I'll get on that. Thanks guys. — ParamoreBaby
– ParamoreBaby, Commented Dec 3, 2013 at 18:53
I think this will help you [Two Dimensional String Array][1] [1]: stackoverflow.com/questions/19173396/… — suraj_fale
– suraj_fale, Commented Dec 3, 2013 at 18:58

theGreenCabbage · Accepted Answer · 2013-12-03 19:17:31Z

8

Looks like this is what you want

    int columns = 2;
    int rows = 2;

    String[][] newArray = new String[columns][rows];
    newArray[0][0] = "France";
    newArray[0][1] = "Blue";

    newArray[1][0] = "Ireland";
    newArray[1][1] = "Green";

    for(int i = 0; i < rows; i++){
        for(int j = 0; j < columns; j++){
            System.out.println(newArray[i][j]);
        }
    }

Here I'll explain the code:

This declares the size of your new 2D array. In Java (and most programming languages), your first value starts at 0, so the size of this array is actually 2 rows by 2 columns

    int columns = 2;
    int rows = 2;

Here you are using the type String[][] to create a new 2D array with the size defined by [rows][columns].

    String[][] newArray = new String[columns][rows];

You assign the values by its placement within the array.

    newArray[0][0] = "France";
    newArray[0][1] = "Blue";

    newArray[1][0] = "Ireland";
    newArray[1][1] = "Green";

Looping through i would loop through the rows, and looping through j would loop through the columns. This code loops through all rows and columns and prints out the values in each index.

    for(int i = 0; i < rows; i++){
        for(int j = 0; j < columns; j++){
            System.out.println(newArray[i][j]);
        }
    }

Alternatively, assignment can be a one-liner:

    String[][] newArray = {{"France", "Blue"}, {"Ireland", "Green"}};

But I don't like this way, as when you start dealing with larger sets of data (like 10,000+ points of data with many columns), hardcoding it in like this can be rough.

edited Dec 3, 2013 at 19:17

answered Dec 3, 2013 at 19:03

theGreenCabbage

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4 Comments

theGreenCabbage Over a year ago

My homework for you is to not write it procedurally but write it objectively ;-). I think that's what the exercise would have wanted too.

theGreenCabbage Over a year ago

Any reply? Feedback? Questions?

theGreenCabbage Over a year ago

Np. Now do it objectively! I'll start you off with the instance variable as String[][] newArray.

travisjayday Over a year ago

Why is it String[][] newArray = new String[columns][rows]; and not String[][] newArray = new String[rows][columns];? I thought rows go before columns in initializing and accessing a 2d array.

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