Thread: Modify class fields

Hello,
I am trying to remove values from lists.

    private List<Node> nodes;
    private List<Edge> edges;
 
 
    public List<Edge> getEdgeTo(Node x) {
        List<Edge> edges1 = new ArrayList<Edge>();
        for (int i = 0; i < edges.size(); i++) {
            if (edges.get(i).getFirstNode().getId() == x.getId() || edges.get(i).getSecondNode().getId() == x.getId()) {
                edges1.add(edges.get(i));
            }
        }
        return edges1;
    }
 
    private void removeEdge(Node x) {
        List<Edge> edges2 = getEdgeTo(x);
        for (int i = 0; i < edges2.size(); i++) {
            edges.remove(i);
        }
 
    }
 
    private void removeNode(Node x) {
        for (int i = 0; i < nodes.size(); i++) {
            if(nodes.get(i).getId() == x.getId()){
                nodes.remove(x);
            }
        }
 
    }

But when i try to run method that uses this functions it works
incomprehensible to me.

public Map<Node, Node> findNextHospital(Node start) {
        Node current = start;
        Map<Node, Node> minDistances = new HashMap<Node, Node>();
        calculateShortestPathFromSource(current);
        Node nextHospital = getMinimumDistanceOfAll(current);
        System.out.println("Next hospital " +nextHospital.getId());
        minDistances.put(current, nextHospital);
        removeNode(current);
        removeEdge(current);
        System.out.println("Before");
        System.out.println("Nodes size "+ nodes.size() + "Edges size"+edges.size());
        for(int i=0;i<nodes.size();i++){
            System.out.println(nodes.get(i).getId());
        }
        for(int i=0;i<edges.size();i++){
            System.out.println(edges.get(i).getSecondNode().getId() + " " + edges.get(i).getFirstNode().getId());
        }
 
        current = nextHospital;
 
        System.out.println("current id "+ current.getId());
        calculateShortestPathFromSource(current);
        Node nextHospital1 = getMinimumDistanceOfAll(current);
        System.out.println("Next hospital "+nextHospital1.getId());
        minDistances.put(current, nextHospital1);
        removeNode(current);
        removeEdge(current);
        for(int i=0;i<nodes.size();i++){
            System.out.println(nodes.get(i).getId());
        }
        for(int i=0;i<edges.size();i++){
            System.out.println(edges.get(i).getSecondNode().getId() + " " + edges.get(i).getFirstNode().getId());
        }
        System.out.println("After");
        System.out.println(nodes.size());
        System.out.println(edges.size());
        return minDistances;
    }

Result of running this function looks like this:
Next hospital 3
Before
Nodes size 4Edges size10
1
2
3
4
3 0
2 1
4 3
0 1
0 3
3 1
1 2
1 4
3 4
4 2
current id 3
Next hospital 0
1
2
4
2 1
0 1
3 1
1 4
4 2
After
3
5
2

Numbers of nodes and edges have decreased but list still containts some edges to Node with id 0 despite of fact that all should be removed. Also node with id 0 when I check if nodes list containts it returns boolean false value. But then "Next hospital 0" has id 0 but node with this id shouldn't exist.

i tried using edges.removeAll(edges2) instead of previous method and it works fine to my surprise now