Topological Sort in Java

topologicalSort.java

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.LinkedList;
import java.util.Stack;
import java.util.StringTokenizer;

class GeneratedGraph {
	public boolean error = false; // eroare graf ciclic
	public int n; // numar de noduri
	public LinkedList<Integer>[] list;// lista de adiacenta

	@SuppressWarnings("unchecked")
	GeneratedGraph(int n) {
		this.n = n;
		list = new LinkedList[n];
		for (int i = 0; i < n; i++) {
			list[i] = new LinkedList<>();
		}
	}

	void addEdge(int a, int b) {
		list[a].add(b); // adauga muchie de la a la b
	}

	void exploreForTopologicalSort(Stack<Integer> s, int[] visited, int x) {
		// marcheaza ca vizitat
		visited[x] = 1; // gri
		for (int iter : list[x]) {
			if (visited[iter] == 1) {
				error = true;
				break;
			}
			if (visited[iter] == 0) {
				exploreForTopologicalSort(s, visited, iter);
			}
		}
		visited[x] = 2;// negru
		s.push(x);
	}

	void topologicalSort() {
		Stack<Integer> s = new Stack<Integer>();
		int[] visited2 = new int[n];
		for (int i = 0; i < n; i++) {
			visited2[i] = 0;// alb
		}
		for (int i = 0; i < n; i++) {
			if (visited2[i] == 0) {
				exploreForTopologicalSort(s, visited2, i);
				if (error == true) {
					System.out.println("Graf Ciclic");
					return;
				}
			}
		}
		while (!s.empty()) {
			System.out.print(s.pop() + " ");
		}
	}
}

public class Permutari {
	private static BufferedReader br;

	public static void main(String[] args) throws IOException {
		FileReader file = new FileReader("file");
		br = new BufferedReader(file);
		GeneratedGraph g = new GeneratedGraph(n);
		g.addEdge(1,2);
		//...
		// sortarea topologica pe graf
		g.topologicalSort();
		br.close();
		file.close();
	}
}