Comparing a 2 dimensional array to a single dimensional array in Java

Question

Does anyone know why this doesn't compile?

public class ArrayCompare{

   public static void main (String []args){

      String words= "Hello this is a test";

      String delimiter=" ";
      String [] blocker=words.split(delimiter);

      String [][] grid= new String [100][100];

      grid[0]="Hello";

           if (grid[0].equals(blocker[0])){
                 System.out.print("Done!");
   }
        }
             }

I would like to perform this function of comparison using a 2 dimensional array. I am a newbie! Please help if you can. Thanks in advance!

grid[0] is array of string. It is impossible to assign string to array of string. — turbanoff
– turbanoff, Commented Mar 30, 2012 at 3:51
Do you want to compare each String in grid to blocker[i]? If so, you need a nested loop — Chetter Hummin
– Chetter Hummin, Commented Mar 30, 2012 at 3:51

Óscar López · Accepted Answer · 2012-03-30 03:51:31Z

1

Try this:

grid[0][0]="Hello";

grid is a two-dimensional array. For the same reason, you need to do this:

if (grid[0][0].equals(blocker[0]))

answered Mar 30, 2012 at 3:51

Óscar López

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Comments

Luiggi Mendoza · Accepted Answer · 2012-03-30 03:51:18Z

0

grid[0] is a String[] type, not a String. So your code should be like this

grid[0] = new String[100];
grid[0][0] = "Hello";
if (grid[0][0].equals(bloker[0])) {
    //your logic...
}

answered Mar 30, 2012 at 3:51

Luiggi Mendoza

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2 Comments

vegadoom Over a year ago

"grid[0][0] == bloker[0]" No! Don't do this! This is comparing references, which will not be equal. You need to use grid[0][0].equals(blocker[0]). This is true in general in Java.

vegadoom Over a year ago

But that's extremely bad practice, it shouldn't be shown to a newbie especially, and not true in the general case.

vegadoom · Accepted Answer · 2012-03-30 03:51:34Z

0

String [][] grid= new String [100][100];

  grid[0]="Hello";

There's your problem. You are trying to assign a string to a string array. Think of a 2d array as an array of arrays.

You probably want something like

grid[0][0]="Hello!";

answered Mar 30, 2012 at 3:51

vegadoom

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Comments

kandarp · Accepted Answer · 2012-03-30 03:54:01Z

0

grid is 2d array. you can't do like d[0] = "Hello". So, if you want to assign value at 0 position

d[0][0] = "Hello";

 if (grid[0][0].equals(blocker[0])){
System.out.print("Done!");
 }

answered Mar 30, 2012 at 3:54

kandarp

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Comments

ring bearer · Accepted Answer · 2012-03-30 03:56:13Z

0

It won't compile because grid[0] is not String type. It is String[] (Array) type. Variable grid[0] is actually pointing to a String[100] array.

You are attempting to assign a string "Hello" to an array by

grid[0]="Hello"; statement.

If you want to assign a string to a location in grid, you must provide two index(s) - following is legal:

grid[0][0]="Hello";

May I suggest using eclipse or BlueJ to edit your Java code? so that such basic errors are shown on real-time and explained well?

edited Mar 30, 2012 at 3:56

answered Mar 30, 2012 at 3:51

ring bearer

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1 Comment

ring bearer Over a year ago

@user1299661, if an answer was helpful, consider upvote (arrow on left) or accepting the answer - that will improve your chances of getting questions answered in SO in future.

Akash Yadav · Accepted Answer · 2012-03-30 07:01:55Z

0

First thing you can't assign value to the element of the multi dimensional array using single index

grid[0]="Hello";
you need to specify both the indices like grid[0][0] = "Hello" this will set the 0th element of 0th row to Hello

Likewise while compairing if (grid[0].equals(blocker[0])){ System.out.print("Done!"); you have to pass the same indices here (You cannot compare a String to a Array Object) if (grid[0][0].equals(blocker[0])){ System.out.print("Done!");

answered Mar 30, 2012 at 7:01

Akash Yadav

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