Java: Array Index Out of Bound Exception

Question

When I compiled I got here error java.lang.ArrayIndexOutOfBoundsException: -1. I checked code 3 times and no error found there, also I am not writing after end of array.

Random nahoda = new Random();    int[][] minPol = new int[5][5];
int[][] cisPol = new int[5][5];
for(int i = 0;i<5;i++)
{
for(int j=0;j<5;j++)
{
minPol[i][j] = nahoda.nextInt(2);
cisPol[i][j] = 0;
}
}
for(int i = 0;i<5;i++)
{
    for(int j=0;j<5;j++)
    {
        if(minPol[i][j]!=0)
        {
        if(i != 0 || j != 0 || i != 4 || j != 4)
        {
            cisPol[i+1][j+1]++;
            cisPol[i+1][j-1]++;
            cisPol[i-1][j+1]++;
            cisPol[i-1][j-1]++;
            cisPol[i+1][j]++;
            cisPol[i-1][j]++;
            cisPol[i][j+1]++;
            cisPol[i][j-1]++;
        }
        else
        {
            if(i == 0)
            {
                if(j == 0)
                {
                    cisPol[i+1][j+1]++;
                    cisPol[i][j+1]++;
                    cisPol[i+1][j]++;
                }
                else if(j == 4)
                {
                    cisPol[i+1][j]++;
                    cisPol[i+1][j-1]++;
                    cisPol[i][j-1]++;
                }
                else
                {
                    cisPol[i+1][j+1]++;
                    cisPol[i][j+1]++;
                    cisPol[i+1][j]++;
                    cisPol[i+1][j-1]++;
                    cisPol[i][j-1]++;
                }
            }
            else if(i == 4)
            {
                if(j == 0)
                {
                    cisPol[i-1][j+1]++;
                    cisPol[i-1][j]++;
                    cisPol[i][j+1]++;
                }
                else if(j == 4)
                {
                    cisPol[i-1][j-1]++;
                    cisPol[i-1][j]++;
                    cisPol[i][j-1]++;
                }
                else
                {
                    cisPol[i][j-1]++;
                    cisPol[i][j+1]++;
                    cisPol[i-1][j+1]++;
                    cisPol[i-1][j]++;
                    cisPol[i-1][j-1]++;
                }
            }
        }            
        }
    }
}

I am beginner in Java and thanks for tips

when i=4 or j=4„ the index goes out of bounds because of i+1 or j+1 indexes respectively. — Shashank Kadne
– Shashank Kadne, Commented Nov 12, 2012 at 15:02

Jon Skeet · Accepted Answer · 2012-11-12 15:01:21Z

7

Look at this condition:

if(i != 0 || j != 0 || i != 4 || j != 4)

That doesn't do what you want it to. It will always be true, because i can't be simultaneously equal to 0 and 4.

Therefore you'll end up going into here when j is 0:

cisPol[i+1][j-1]++;

Bang.

answered Nov 12, 2012 at 15:01

Jon Skeet

1.5m893 gold badges9.3k silver badges9.3k bronze badges

Sign up to request clarification or add additional context in comments.

Comments

mwangi · Accepted Answer · 2012-11-12 15:10:15Z

0

Try this;

Replace this line;

 if(i != 0 || j != 0 || i != 4 || j != 4)

with

 if( i>=1 && j>=1 && j<4 && i<4)

That will make sure you don't reference from your array with a negative index or a value greater than 4.

answered Nov 12, 2012 at 15:10

mwangi

1,6261 gold badge20 silver badges23 bronze badges

Collectives™ on Stack Overflow

Java: Array Index Out of Bound Exception

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related