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up vote 0 down vote favorite

I'm working on a program that requires me to take in a 1-D String array from a file and turn it into a 2-D array. Taking in the array from the file works fine, but I can't get the second part to work.

The code I'm working with is:

char[][] array2 = new char [7][5];

for (int i = 0; i < array1.length; i++)
{
    array2[i]= array[i].toCharArray();   
}

for (int i = 0; i < 5; i++)
{
    for (int j = 0; j < 7; j++)
    {
         System.out.println(array2[i][j]);
    }
}

The array is supposed to print in a grid format, but is printing downward.

Any help is appreciated, thanks.

share|improve this question
    
How can a 1d string be converted to a 2d char array? – blackpanther Sep 26 '13 at 13:42
1  
println prints a line break at the end of the line. use print to print without line break – njzk2 Sep 26 '13 at 13:43
    
To add on to @njzk2's comment, use print inside the j loop to print each character in a string in one row, and then immediately following that loop block, use println(); to go to a new line for the next string/char array. – jonhopkins Sep 26 '13 at 13:47
    
It is printing the right way now, but it is only printing out the first row, after that it prints out blank for the rest of the rows. – user2817804 Sep 27 '13 at 15:31
up vote 2 down vote

Use print instead of println in inner loop and after each loop print a blank line with println.

for (int i = 0; i < 7; i++) // see changes 5/7. You did "new char[7][5]" not [5][7]
{
    for (int j = 0; j < 5; j++) // see changes 7/5
    {
         System.out.print(array2[i][j]);
    }
    System.out.println();
}

Update:

Following is a program that convert String array to 2D char array.

public class StringToChar {
    public static void main(String[] args) {
        String[] strArr = { "HELLO", "WORLD" };
        char[][] char2D = new char[strArr.length][];

        for (int i = 0; i < strArr.length; i++) {
            char2D[i] = strArr[i].toCharArray();
        }

        for (char[] char1D : char2D) {
            for (char c : char1D)
                System.out.print(c + " ");

            System.out.println();
        }
    }
}
share|improve this answer
    
Thanks, you wouldnt happen to know why im getting a "java.lang.NullPointerException" after the first line is printed? – user2817804 Sep 26 '13 at 13:56
    
@user2817804 See my updated answer. – TheKojuEffect Sep 26 '13 at 13:59
    
Thanks again, the exception is gone. Now i just need to figure out why the array only prints out one line and ignores the rest. – user2817804 Sep 26 '13 at 14:03
    
@user2817804 :). Actually, your question is quite incomplete. However, if you feel like you've got your answer, you can close this question. – TheKojuEffect Sep 26 '13 at 14:09
    
Well since you asked lol, any idea why the array is only printing out the first line? Could there be a an issue coming from changing the 1d string to the 2d char? – user2817804 Sep 26 '13 at 14:33
up vote 1 down vote

few suggestions,

  1. replace char[][] array2 = new char [7][5]; with char[][] array2 = new char [array1.length][]; (where array1 holds your strings), so your 2d array will have as many rows as you have strings
  2. your loop
for (int i = 0; i < 5; i++)
{
    for (int j = 0; j < 7; j++)
....
 }

change to 

for (int i = 0; i < array2.length; i++)
{ 
   for (int j = 0; j <  array2[i].length; j++)
....

another thing is if you want your string printed in rows, use System.out.print, and whenever you finished inner loop, print out'\n' character

share|improve this answer
up vote 0 down vote

You are using println, which is why each character is printed on its own line. You must use print instead.

Note that your initialization with

new char [7][5];

doesn't work as you expect because the inner arrays will be overwritten. Use

new char[7][]

for the same result, but more clarity as to your intent. Here

for (int i = 0; i < 5; i++)
   for (int j = 0; j < 7; j++)

you have apparently reversed the order of indices: you are iterating only through 5 outer arrays, but you have allocated 7. What you should do instead is check against the actual array length and not a hardcoded number. The inner array may be of any size, after all (it depends on the string length).

share|improve this answer
up vote 0 down vote

Have a look at the String.toCharArray()

If it is printing downwards then change 

  for (int i = 0; i < 7; i++)  //row loop
  {
    for (int j = 0; j < 5; j++) //column loop
     {
        System.out.print(array2[i][j]);
     }
    System.out.println(); //add here 
  }

Have a look at

  1. formatting
  2. print vs println
share|improve this answer
    
array1 is probably an array of String, here – njzk2 Sep 26 '13 at 13:57
    
@njzk2: ohh! I missed that. Thanks Sir. – Aniket Kulkarni Sep 26 '13 at 14:02

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