Having problem with Ajacency Graph

[kursist]

hi, I have problem with this code. I want to return an Iterator<Edge<E>> in incidentEdges(xx) method but it gives error. Some type missmatch,, why

public class AdjacencyListGraph<V,E> implements Graph<V,E>{
	private List<Vertex<V>> vertices; //the vertices of the graph
	private List<Edge<E>> edges; //the edges of the graph
....
	@Override
	public Iterator<Edge<E>> incidentEdges(Vertex<V> v)
	{
		ALVertex vertex = check(v);
		Iterator<Edge<E>> iter = vertex.getEdges().iterator();
                return  iter;
	}
....
}


private class ALVertex implements Vertex<V>{
		private V element;
		private ArrayList<ALEdge> edges = new ArrayList<ALEdge>();
....
		public ArrayList<ALEdge> getEdges(){
			return edges;
		}
.....
}


private class ALEdge implements Edge<E>{
             private E element;
....
		@Override
		public E element()
		{
			return element;
		}
....
}

Adv.
Thanks

[Norm]

but it gives error. Some type missmatch

When you get errors, please copy and paste here the full text of the error message. That will speed things up.

Also please surround your code with code tags. See: http://www.java-forums.org/misc.php?do=bbcode#code

[kursist]

When you get errors, please copy and paste here the full text of the error message. That will speed things up.

Also please surround your code with code tags. See: BB Code List - Java Forums

Here is what it says. I use eclipse. ALEdge is inner class and it implements Edge<E>.


Type mismatch: cannot convert from Iterator<AdjacencyListGraph<V,E>.ALEdge> to Iterator<Edge<E>>


Thanks,
kurs

[Norm]

cannot convert from Iterator<AdjacencyListGraph<V,E>.ALEdge> to Iterator<Edge<E>>

Is that true? Can you convert the one type to the other? The compiler doesn't see how to do it.

Your posting of the error didn't show the source line that caused the error.

[kursist]

Is that true? Can you convert the one type to the other? The compiler doesn't see how to do it.

Your posting of the error didn't show the source line that caused the error.

The code is here. Cast doesn't work.
Edge<E> is interface and the ALEdge is the implementation.

public Iterator<Edge<E>> incidentEdges(Vertex<V> v)
	{
		ALVertex vertex = check(v);
		[B]Iterator<Edge<E>> iter = vertex.getEdges().iterator();[/B]
                return  iter;
	}

[Norm]

What don't you understand about the error message?
The compiler finds one type on the left of the = and another type on the right and says there is a mismatch.

Sort of the same as: int i = "ASTRING";

Can you post a small program that will compile and give the error you are getting. What you've posted is missing too many parts.

[kursist]

What don't you understand about the error message?
The compiler finds one type on the left of the = and another type on the right and says there is a mismatch.

Sort of the same as: int i = "ASTRING";

Can you post a small program that will compile and give the error you are getting. What you've posted is missing too many parts.

You are right. The cause to this problem was at ALVertex class.

private class ALVertex implements Vertex<V>{
		private V element;
		//private ArrayList<[COLOR="red"]ALEdge[/COLOR]> edges = new ArrayList<ALEdge>
               private ArrayList<Edge<E>> edges; = new ArrayList<ALEdge>();
                
                public ALVertex(){
                    
                      edges = new ArrayList<ALEdge>();
               }

....
		public ArrayList<ALEdge> getEdges(){
			return edges;
		}
.....
}

Thank you very much,
Kurs,.

[Norm]

Try compiling it with jdk1.7 -> Much more info in the warning/error message:

Running: D:\Java\jdk1.7.0\bin\javac.exe -Xlint -g -deprecation -classpath D:\JavaDevelopment\;. IteratorProblem.java

IteratorProblem.java:16: warning: [rawtypes] found raw type: IteratorProblem.ALVertex
ALVertex vertex = null; //check(v);
^
missing type arguments for generic class IteratorProblem.ALVertex<V>
where V is a type-variable:
V extends Object declared in class IteratorProblem.ALVertex
IteratorProblem.java:19: warning: [unchecked] unchecked conversion
Iterator<Edge<E>> iter = vertex.getEdges().iterator();
^
required: Iterator<Edge<E>>
found: Iterator
where E is a type-variable:
E extends Object declared in class IteratorProblem.AdjacencyListGraph
IteratorProblem.java:67: warning: [rawtypes] found raw type: IteratorProblem.ALEdge
private ArrayList<ALEdge> edges = new ArrayList<ALEdge>();
^
missing type arguments for generic class IteratorProblem.ALEdge<E>
where E is a type-variable:
E extends Object declared in class IteratorProblem.ALEdge
IteratorProblem.java:67: warning: [rawtypes] found raw type: IteratorProblem.ALEdge
private ArrayList<ALEdge> edges = new ArrayList<ALEdge>();
^
missing type arguments for generic class IteratorProblem.ALEdge<E>
where E is a type-variable:
E extends Object declared in class IteratorProblem.ALEdge
IteratorProblem.java:69: warning: [rawtypes] found raw type: IteratorProblem.ALEdge
public ArrayList<ALEdge> getEdges(){
^
missing type arguments for generic class IteratorProblem.ALEdge<E>
where E is a type-variable:
E extends Object declared in class IteratorProblem.ALEdge
5 warnings

6 error(s)