我不断地得到这个错误:java.lang。ArrayIndexOutOfBoundsException:12

My program basically takes a list of ISBN numbers and determines if they're valid or not. So the error is at: s1[l]=digits[i][l-1]+digits[i][l]; This line of code takes the partial sum of the ISBN numbers using the for-loop. The other loop below it takes the partial sum of all the ints in the array s1. Help please? The error is: My program basically takes a list of ISBN numbe