Write a program in Java to implement the topological sorting algorithm. Assume that the vertices of the digraph are lowercase letters. The main() method in your program should prompt the user to enter the values of the adjacency matrix representing the digraph. The main() method should then print the adjacency matrix. Finally the main() method should call the topoSort() method to topologically sort the matrix. The topoSort() method should display the topologically sorted vertices of the digraph.

I am not sure how to go about coding the topological sort. I've tried creating a function outside of main that makes arrays out of the columns of the given matrix, then label them alphabetically. I wasn't successful. Here is my code, please help!