------------------MyData.java------------------

     

    public class MyData {

        public String job;

    	public String [] others;

    	public MyData(String job, String [] other) {

    		this.job = job;

    		this.others = other;

    	}

    }

     

    ---------------TopSort.java-------------------

    import java.util.HashMap;

    import java.util.HashSet;

    import java.util.LinkedList;

    import java.util.Map;

    import java.util.Queue;

    import java.util.Set;

    import java.util.Iterator;

     

    public class TopSort {

     

    	public static String[] topologicalSort(MyData[] data) throws Exception {

    		/*

    		 * Q ? Set of all nodes with no incoming edges while Q is non-empty do

    		 * remove a node n from Q output n for each node m with an edge e from n

    		 * to m do remove edge e from the graph if m has no other incoming edges

    		 * then insert m into Q if graph has edges then output error message

    		 * (graph has a cycle)

    		 */

    		int n = data.length;

    		Map graph = new HashMap();

    		Queue q = new LinkedList();

    		String[] sorted = new String[n];

    		// Graph construction

    		for (int i = 0; i < data.length; i++) {

    			// for each statistic name s

    			graph.put(data[i].job, new HashSet());

    			String[] requiredJobs = data[i].others;

    			for (int j = 0; j < requiredJobs.length; j++) {

    				// for each String si in requiredStats

    				((Set) graph.get(data[i].job)).add(requiredJobs[j]);

    			}

    			// Initial nodes in q

    			if (((Set) graph.get(data[i].job)).size() == 0)

    				q.add(data[i].job);

    		}

     

    		// Getting the nodes in sorted order

    		int index = 0;

    		while (q.size() > 0) {

    			String s = (String) q.remove();

    			sorted[index++] = s;

    			Iterator iter = graph.keySet().iterator();

    			while (iter.hasNext()) {

    				// for each key in graph

    				// check if node is not already removed

    				Object key = iter.next();

    				if (((Set) graph.get(key)).size() != 0) {

    					((Set) graph.get(key)).remove(s);

    					// if this node now has zero incoming edges

    					if (((Set) graph.get(key)).size() == 0) {

    						q.add(key);

    					}

    				}

    			}

    		}

     

    		if(index
    			  throw new Exception("Cycle detected, exiting ....");

     

    		return sorted;

    	}

     

    	public static void main(String[] args) throws Exception {

    		MyData d1 = new MyData("job1",new String [] {"job3","job5","job4"});

    		MyData d2 = new MyData("job3",new String [] {"job5","job6"});

    		MyData d3 = new MyData("job4",new String [] {"job2","job7"});

    		MyData d4 = new MyData("job7",new String [] {"job1","job2","job4"});

    		String [] sorted = TopSort.topologicalSort(new MyData [] {d1,d2,d3,d4});

    		for (int i = 0; i < sorted.length; i++) {

    			System.out.println(sorted[i]);

    		}

     

    		

    	}

     

    }