I am implementing a scalingFordFulkerson Algorithm, however i need help with this error and how to solve it when input a graph i should get the maxflow and the run time. java code

ResidualGrappBuilder.java code

import graphCode.Edge;

import graphCode.SimpleGraph;

import graphCode.Vertex;

import java.util.Iterator;

public class ResidualGraphBuilder $\{$

public static SimpleGraph build$($SimpleGraph graph, Vertex source, Vertex sink, double scalingFactor$)\{$

SimpleGraph residualGraph $=$ new SimpleGraph$()$;

VertexAttributes sourceData $=$ new VertexAttributes$($true$)$;

source.setData$($sourceData$)$;

residualGraph.getVertexList$().$add$($source$)$;

for $($Iterator edgeIter $=$ source.getIncidentEdgeList$().$iterator$()$; edgeIter.hasNext$()$; $)\{$

Edge edge $=($Edge$)$ edgeIter.next$()$;

Vertex neighbor $=$ graph.opposite$($source$,$ edge$)$;

$//$error is on this line

if $($isEligibleEdge$($neighbor$,$ edge, scalingFactor$))\{$

residualGraph.getEdgeList$().$add$($edge$)$;

residualGraph.getVertexList$().$add$($neighbor$)$;

if $($neighbor $==$ sink$)\{$

return residualGraph;

$\}$

SimpleGraph subGraph $=$ build$($graph$,$ neighbor, sink, scalingFactor$)$;

if $($subGraph$.$getVertexList$().$getLast$()==$ sink$)\{$

return subGraph;

$\}$

residualGraph.getEdgeList$().$removeLast$()$;

$\}$

$\}$

residualGraph.getVertexList$().$removeLast$()$;

return residualGraph;

$\}$

private static boolean isEligibleEdge$($Vertex neighbor, Edge edge, double scalingFactor$)\{$

VertexAttributes neighborData $=($VertexAttributes$)$ neighbor.getData$()$;

EdgeAttributes edgeAttributes $=($EdgeAttributes$)$ edge.getData$()$;

$//$error in the line below

boolean notVisited $=!$neighborData.isVisited$()$;

boolean hasResidualCapacity $=$ edgeAttributes.getResidualCapacity$()>=$ scalingFactor;

boolean hasBackwardFlow $=$ edgeAttributes.getCurrentFlow$()>=$ scalingFactor;

return notVisited && $($hasResidualCapacity $||$ hasBackwardFlow$)$;

$\}$

$\}$

main.java

public static double calculateMaxFlow$($SimpleGraph graph, Vertex source, Vertex sink$)\{$

double totalFlow $=0$; $//$ Total flow

double maxCapacity $=$ GraphUtils.findMaxEdgeCapacity$($graph$)$; $//$ Find max edge capacity

double scalingFactor $=$ GraphUtils.findInitialScalingFactor$($graph$,$ source$)$; $//$ Start with highest power of $2$

$//$ Process scaling levels

while $($scalingFactor $>=1)\{$

$//$ Build the residual graph for the current scaling level

$//$Error here

SimpleGraph residualGraph $=$ ResidualGraphBuilder.build$($graph$,$ source, sink, scalingFactor$)$;

$//$ Augment flow while paths exist

while $($residualGraph$.$numEdges$()>0)\{$

double flowToAdd $=$ PathProcessor.processAugmentingPath$($residualGraph$,$ source$)$;

totalFlow $+=$ flowToAdd; $//$ Update total flow

PathProcessor.updateOriginalGraph$($graph$,$ residualGraph, flowToAdd$)$;

residualGraph $=$ ResidualGraphBuilder.build$($graph$,$ source, sink, $0)$; $//$ Rebuild residual graph

$\}$

$//$ Halve the scaling factor

scalingFactor $/=2$;

$\}$

return totalFlow;

$\}$

$\}$

Vertex Attributes.java file

package scalingFlowAlgorithm;

public class VertexAttributes $\{$

private boolean visited;

public VertexAttributes$()\{$

this.visited $=$ false;

$\}$

public VertexAttributes$($boolean visited$)\{$

this.visited $=$ visited;

$\}$

public boolean isVisited$()\{$

return visited;

$\}$

public void setVisited$($boolean visited$)\{$

this.visited $=$ visited;

$\}$

$\}$

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