Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 15

Question

I cannot find my exception although the errors are at

at puzzle.Puzzle.isSafe(Puzzle.java:97)
    at puzzle.Puzzle.main(Puzzle.java:49)
Java Result: 1

I need to print a 15x 15 grid with random words in 6 directions and starts in empty spaces.

My java code is as follows.

/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package puzzle;

//import java.util.Arrays;

import java.util.Random;

/**
*
* @author sony
*/
public class Puzzle {
static char[][] grid;

//class solve= new Puzzle();



/**
 * @param args the command line arguments
 */
public static void main(String[] args) {
     grid =new char[15][15];
    String[] words={"hello","coward","heartbeat","beautiful","kind"};
    String[] direction = {"horizontal","horizontalBack","vertical","varticalUp",
                 "diagonal","diagonalBack"};

int i,j,x,y,dir;
Random randGen = new Random();
    for(i=0; i<15 ;i++)
    {
        for(j=0;j<15;j++)
        grid[i][j]='*';
    }


    for(i=0;i< words.length;i++)
    {
        int set=0;
        while(set!=1)
        {
            x =  randGen.nextInt(15);
            y =  randGen.nextInt(15);
            dir = randGen.nextInt(6);
            if((isSafe(x,y,words[i],direction[dir])))
            {
                place(x,y,words[i],direction[dir]);
                set=1;
            }

        }
    }

    for(i=0; i<15; i++)
     {
      for(j=0;j<15;j++)
          System.out.print(grid[i][j]);
      System.out.println("");
     }


} 
   static boolean isSafe(int x,int y, String word, String d)
   {  int len=word.length();
   int i,k,j;
       if(d.equals("horizontal"))
           for(i=y,k=0;i< (y+len);i++,k++)
           {
               if((grid[x][i]!='*')&& (grid[x][i]!=word.charAt(k)) && ((y+len) >15) )
                   return false;
           }
       if(d.equals("horizontalBack"))
           for(i=y,k=0;i >(y-len);i--,k++)
           {
               if((grid[x][i]!='*')&& (grid[x][i]!=word.charAt(k)) && ((y-len) <0)  )
                   return false;
           }
       if(d.equals("vertical"))
           for(i=x,k=0;i <(x+len);i++,k++)
           {
               if((grid[i][y]!='*')&& (grid[i][y]!=word.charAt(k)) && ((x+len) >15)  )
                   return false;
           }
         if(d.equals("verticalUp"))
           for(i=x,k=0;i >(x+len);i++,k++)
           {
               if((grid[i][y]!='*')&& (grid[i][y]!=word.charAt(k)) && ((x-len) <0)  )
                   return false;
           }
         if(d.equals("diagonal"))
         {   k=0;i=y;j=x;
             while((i< (y+len)) && (j< x+len))               {
               if((grid[i][j]!='*')&& (grid[i][j]!=word.charAt(k)) && ((x+len) >15) &&       ((y+len)>15)   )
               {return false;}
               i++;j++;k++;
           }

         }
         if(d.equals("diagonalBack"))
         {   k=0;i=y;j=x;
             while((i> (y-len)) && (j>x-len))               {
               if((grid[i][j]!='*')&& (grid[i][j]!=word.charAt(k)) && ((x-len)<0) && ((y-len)<0)   )
               {return false;}
               i--;j--;k++;
           }

         }


      return true;       


   }

 static void place(int x, int y, String word, String d)
   {  int len = word.length();
   int i,k,j;
       if(d.equals("horizontal"))
           for( i=y, k=0;i< (y+len);i++,k++)
           {
               grid[x][i]=word.charAt(k);
           }

   if(d.equals("horizontalBack"))
           for( i=y,k=0;i> (y-len);i--,k++)
           {
               grid[x][i]=word.charAt(k);
           }
    if(d.equals("vertical"))
           for( i=x,k=0;i< (x+len);i++,k++)
           {
               grid[i][y]=word.charAt(k);
           }

   if(d.equals("verticalUp"))
           for( i=x,k=0;i> (x-len);i--,k++)
           {
               grid[i][y]=word.charAt(k);
           }
   if(d.equals("diagonal"))
   { i=y;j=x;k=0;
           while((i< (y+len)) && (j< (x+len))) 
           {
               grid[i][j]=word.charAt(k);
               i++;j++;k++;

           }

   }
   if(d.equals("diagonalUp"))
   { i=y;j=x;k=0;
           while((i> (y-len)) && (j> (x-len))) 
           {
               grid[i][j]=word.charAt(k);
               i--;j--;k++;

           }

   }




   }

}

Answer 1

Please note the typo. varticalUp in the array declaration and verticalUp in the if condition. Although this is not the cause of the problem but its worth noting it.

Answer 2

Instead of telling you how to fix your code, I'll help you understand the error.

Log

at puzzle.Puzzle.isSafe(Puzzle.java:97)
    at puzzle.Puzzle.main(Puzzle.java:49)
Java Result: 1

Puzzle.java:97

if (grid[i][j]!='*' && grid[i][j]!=word.charAt(k) && (x+len)>15 && (y+len)>15)

Exception

Exception java.lang.ArrayIndexOutOfBoundsException means that either:

• i >= grid.length

• j >= grid[i].length

Detail

grid.length and grid[i].length are determined when the array is created:

grid = new char[15][15];

grid.length is 15

grid[i].length is 15

Moreover

Also, there is the string word:

for (i=y, k=0; i < (y+len); i++, k++)
    word.charAt(k);

This will cause an issue too, when k at some point becomes k >= word.length() so that loop should be like this:

for (i=y, k=0; i < (y+len) && k < word.length(); i++, k++)
    word.charAt(k);

Answer 3

I just quickly went through your code and it seems that the problem is in your variable len. See the statement int len=word.length(); on line 68. In fact it should be int len=word.length()-1; because the array index starts from 0. I have not tested it, but you can give it a try.

Answer 4

I can see two bugs.

(1) The line that reads

for(i=x,k=0;i >(x+len);i++,k++)

should read

for(i=x,k=0;i >(x-len);i--,k++)

I think it's line 89.

(2) The bug that's causing this exception is the fact that every time you've got a whole lot of conditions separated by &&, the first one should be && and the subsequent ones should be ||.

For example,

if((grid[x][i]!='*')&& (grid[x][i]!=word.charAt(k)) && ((y+len) >15)) {

should read

if((grid[x][i]!='*')&& (grid[x][i]!=word.charAt(k)) || ((y+len) >15)) {

because you need to return that this square is an unsafe place to start the word if y + len > 15 regardless of what is found at each of the grid squares that you're checking. Similarly, with all the other conditions that look like this.