If the specific conditions are incorrect, I can’t return anything

I'm writing a matrix class. I've written a getnumber method that returns the number in a specific slot in the matrix What should I do if a particular slot does not exist? I'm stuck here:

public int getNumber(int row,int column)
{  
    if (row < matrix.length && column < matrix[0].length) {
        return data[row][column];
    } else {
        //what Now then?
    }
}

After returning the type integer, I don't want to return null because it's not a good design What's the best way to do this? I've considered abandoning the index out of boundary exception, but I don't think it's a good idea because it won't change anything

Solution

Since your code checks the boundaries of the input, you should throw instead of return:

public int getNumber(int row,int column) {  
    if (row >= matrix.length || column >= matrix[0].length) {
        throw new indexoutofboundsexception("("+row+","+column+") is not a valid pair of indexes.");
    } 
    return data[row][column];
}

The reason you should throw instead of silently return is that going beyond the boundary is a programming error The caller should fix it by not calling first, not by checking the return value