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.

So the part I'm stuck in is the topoSort(), I can't seem to find any references that use the adjacency matrix. Everything is either using the graph or linked list. Here is my code so far:

public static void main(String[] args)

{

int i, j, vert;

int arr[][];

System.out.print("Enter the number of vertices in the digraph (max of 10): ");

Scanner input = new Scanner(System.in);

vert = input.nextInt();

while(vert > 10)

{

System.out.print("Max of 10. Please try again! Enter the number of vertices in the digraph (max of 10): ");

vert = input.nextInt();

}

arr = new int[vert][vert];

for(i = 0; i < vert; i++)

{

for(j = 0; j < vert; j++)

{

System.out.print("Enter the value for arr [" + i + "][" + j + "]: ");

arr[i][j] = input.nextInt();

}

}

input.close();

System.out.println("The Adjacency matrix is:");

for(i = 0; i < vert; i++)

{

for(j = 0; j < vert; j++)

{

System.out.print(arr[i][j] + " ");

}

System.out.println();

}

}

}