can not initialize a two dimensional array in java using for loop

Question

I can not initialize a two dimensional array using for loop

import java.util.Scanner;

   public class Quater{
      public static void main(String[] args){
        //declare an array
        double product[][]=new double[3][2];

        //declare a Scanner object
        Scanner userInput=new Scanner(System.in);

        //ask the user for input

        System.out.println("Please enter your data");
        for(int i=0;i<=1;i++)
        {
          for(int j=0;j<=2;j++){
          System.out.println(" enter your data");

          product[i][j]=userInput.nextDouble();
        } 
      }
    }
  }

The problem is when I try to enter the third number, This shut down and not working, however, if I make it new double[100][100], this can work and allow me to enter 6 number.

What about it is "not working"? Be specific. If you have a stack trace, include that, too. — Makoto
– Makoto, Commented Mar 5, 2014 at 22:43

Warlord · Accepted Answer · 2014-03-05 22:45:28Z

7

The outer cycle iterates over rows and inner over columns, therefore you need to have an array of dimensions double[2][3], not double[3][2] that you use.

answered Mar 5, 2014 at 22:45

Warlord

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Comments

ajb · Accepted Answer · 2014-03-05 22:44:36Z

1

If you make your array new double[3][2], then you can access product[i][j] where i goes up to 3-1=2, and j goes up to 2-1=1. That is, the bounds of the indexes in the same order in which they appear in the new. But you're trying to access product[i][j] where j is 2.

answered Mar 5, 2014 at 22:44

ajb

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Comments

RMachnik · Accepted Answer · 2014-03-06 07:56:19Z

1

Corrected code. Look on this. Condition of two fors was fixed. You should do it using length and better is using '<' not '<='. That prevent you from many ArrayIndexOutOfBoundsException .

public static void main(String[] args){
            //declare an array
            double product[][]=new double[3][2];

            //declare a Scanner object
            Scanner userInput=new Scanner(System.in);

            //ask the user for input

            System.out.println("Please enter your data");
            for(int i=0;i<product.length;i++)
            {
                for(int j=0;j<product[i].length;j++){
                    System.out.println(" enter your data");

                    product[i][j]=userInput.nextDouble();

                }
            }
        }

to see the efect you can simply paste down that code.

for (double[] doubles : product) {
                for (double aDouble : doubles) {
                    System.out.println(aDouble);
                }
            }

edited Mar 6, 2014 at 7:56

answered Mar 5, 2014 at 22:46

RMachnik

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3 Comments

Luiggi Mendoza Over a year ago

More than corrected code, you should explain what was wrong, how to fix it and why this fix works.

Luiggi Mendoza Over a year ago

OutOfArrayExceptions you mean ArrayIndexOutOfBoundsException

RMachnik Over a year ago

Yes ArrayIndexOutOfBoundsException :)

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