While coding, I noticed an interesting outcome. I created a 2D char array with a declared size of char[10][10]. However, I found that I could assign char arrays with more characters than the specified size to its rows. Let me demonstrate:
char[][] positions = new char[10][10];
for(int i = 0; i < 10; i++) {
positions[i] = f.readLine().toCharArray();
}
here, if f.readLine().toCharArray() creates an array with more than 10 characters, the 2D array still seems to accept it. When I print out the positions array using a double for-each loop, it even includes the extra characters.
For example, if the input is
aaaaaaaaaa
bbbbbbbbbb
cccccccccc
dddddddddd
eeeeeeeeee
ffffffffff
gggggggggggg - (12 characters long, 2 extra)
hhhhhhhhhh
iiiiiiiiii
jjjjjjjjjj
The output includes all of the exact characters, including the 2 extra ones from gggggggggggg!
I’m not encountering any errors, but I find it interesting that this works since a 2D array isn’t a list and requires set sizes. Does this behavior cause any potential issues, or is it perfectly fine to do this? Just curious, thanks!
The line:
char[][] positions = new char[10][10];
… is equivalent in every way to the following:
char[][] positions = new char[10][];
for (int i = 0; i < 10; i++) {
positions[i] = new char[10];
}
positions is just an array, each of whose elements is a char[]. You can overwrite each value as you like.
Setting positions[i] = ... discards whatever character array happened to be in positions[i] before -- it could even be null -- and replaces it with a reference to a new array.
Hopefully this makes sense. The new char[10][10] syntax is just convenient syntactic sugar for creating a bunch of new arrays; it is not binding on the dimensions of the inner arrays in future.