[FIXED] LinkedList<Edge> becomes (randomly ? ) a String

Issue

I have this program that creates a graph and I implemented it by doing LinkedList<LinkedList> where Edge is

public class Edge<T>{
    T src;
    T value;
    T weight;
    public Edge(T src, T value, T weight){
        this.src=src;
        this.value=value;
        this.weight=weight;
    }

    @Override
    public boolean equals(Object obj){
        if(obj instanceof Edge){
            Edge edge=(Edge) obj;
            return edge.src==src && edge.value==value && edge.weight==weight;
        }
        System.out.println("non e' ramo");
        return false;
    }
    
    @Override
    public String toString(){
        return "["+src+"->"+value+" ("+weight+")]";
    }
}

Here it's the main class that tests the result of the functions in the library In the last line I get this error: expected.get(0) is a String while result is an Edge and they can't be compared

public class GraphTests {
    private static Graph<Integer> test_graph=new Graph<>();


    public static void main(String[] args) throws GraphException {
        test_graph.createGraph(false);
        test_graph.createNode(1);
        test_graph.createNode(5);
        test_graph.createNode(7);

        test_graph.createEdge(1,7,213);
        test_graph.createEdge(1,5,13);
        test_graph.createEdge(5,7,3);
        test_graph.deleteEdge(1,5);

        LinkedList<Edge> result=new LinkedList<>();
        result=test_graph.getEdges();  //the results are correctly inserted in the linked list of edges
        LinkedList<Edge> expected=new LinkedList<>();
        expected.add(new Edge(1,7,213));        //here I am testing just the first Edge
        System.out.println("equals ? "+expected.get(0)==result.get(0));     //the error is HERE
    }
}

I think I tried everything but I still don't get it... Any help would be appreciated

Solution

Try this

var res = expected.get(0)==result.get(0);
System.out.println("equals ?"+res);

The plus (+) is executed before the equal (==) so it The compiler thinks you compare a string to an object The result of the plus (+) is a string

Answered By - Samer Aamar
Answer Checked By - Terry (JavaFixing Volunteer)