Topological Sort

// "static void main" must be defined in a public class.
public class Main {
    public static void main(String[] args) {
        int noOfVertices = 5;
        int[][] adj=new int[][]{
            {0,1,1,0,1},
            {0,0,0,1,0},
            {0,0,0,1,0},
            {0,0,0,0,0},
            {0,0,0,0,0}
        };
        topologicalSort(noOfVertices,adj);
        
        //Graph with Cycle
        noOfVertices = 6;
        adj=new int[][]{
            {0,1,1,0,1,0},
            {0,0,0,1,0,0},
            {0,0,0,1,0,0},
            {0,0,0,0,0,0},
            {0,0,0,0,0,1},
            {0,0,0,0,1,0}
        };
        topologicalSort(noOfVertices,adj);
    }   
    
    static void topologicalSort(int noOfVertices,int[][] adj){
        int[] indegree=new int[noOfVertices];
        
        for(int i=0;i<noOfVertices;i++){
            for(int j=0;j<noOfVertices;j++){
                if(adj[i][j]==1){
                    indegree[j]++;
                }
            }
        }
        
        System.out.println("In-degree Array : "+Arrays.toString(indegree));
        
        Queue<Integer> q=new LinkedList<>();
        
        for(int i=0;i<noOfVertices;i++){
            if(indegree[i]==0){
                q.add(i);
            }
        }
        int topologicalOrder=0;
        System.out.println("Topological Ordering");
        while(!q.isEmpty()){
            int vertex=q.remove();
            System.out.println(vertex+" -> "+(char)(vertex + 'A'));
            topologicalOrder++;
            for(int i=0;i<noOfVertices;i++){
                if(adj[vertex][i]==1){
                    indegree[i]--;
                    if(indegree[i]==0){
                        q.add(i);
                    }
                }
            }
        }
        
        if(topologicalOrder!=noOfVertices){
            System.out.println("Graph has Cycle");
        }
    }
}