Thread: what is this error in hasnext in webgraph

i wrote piece of code ( below) and i work on web graph However, I am using the web graph package include

it.unimi.dsi.webgraph.ImmutableGraph

but show error in

hasnext()

 (while(iter.hasNext()))

and show java doc not found. I work with netbeans.

package aolgraphexample;
 
import java.io.IOException;
import it.unimi.dsi.webgraph.ImmutableGraph;
import it.unimi.dsi.webgraph.NodeIterator;
import it.unipi.di.graph.GraphLabeler;
import it.unipi.di.util.Utils;
 
public class AOLGraphExample {
 
    /**
     * Invoke this class using two parameters: 1) the WebGraph basename (string
     * "webgraph/wg-aol" for the AOL dataset) 2) the GraphLabeler configuration
     * file (string "graphlabeler/graphlabeler.conf" for the AOL dataset)
     */
    public static void main(String[] args) throws Exception {
 
        // -----------------------------------------------------
        // PART ONE
 
        // WebGraph basename
        // String graphFile = args[0];
        String graphFile = "webgraph/wg-aol";
 
        // Name of the GraphLabeler configuration file
        String labelerFile = "graphlabeler/graphlabeler.conf";
 
        System.out.print(" >> Opening databases... ");
 
        // Take the starting time
        long start = System.currentTimeMillis();
 
        // load the graph structure in memory (i.e. WebGraph)
        ImmutableGraph graph = ImmutableGraph.load(graphFile);
 
        // load the data structure for the vertex/edge labels in memory (i.e.
        // GraphLabeler)
        GraphLabeler labeler = GraphLabeler.load(labelerFile);
 
        // print the elapsed time for the first part
        System.out.println("done in: " + Utils.elapsedTime(start, System.currentTimeMillis()));
        // -----------------------------------------------------
 
        System.out.println(" >> Running test N.1");
 
        // [TEST 1]
        //
        // For each vertex, fetch the labels of its adjacent vertices in the
        // graph.
        // This method will fetch ~21.5 million of textual labels (edges are
        // undirected).
        neighborsLabeling(graph, labeler);
 
        System.out.println(" >> Running test N.2");
 
        // [TEST 2]
        //
        // For each vertex, fetch the value of the attribute "click" for each of
        // its outgoing edges.
        // This method will fetch ~21.5 million textual values (edges are
        // undirected).
        // Recall that the available attributes are: "click", "session", "time"
        // and "rank"
        fetchAttribute(graph, labeler, "click");
 
        // close the labeler and release its resources
        labeler.close();
    }
 
    private static void neighborsLabeling(ImmutableGraph graph, GraphLabeler labeler) throws IOException {
 
        // count how many labels has been fetched so far
        int counter = 0;
 
        // the total number of nodes in the graph
        int numNodes = graph.numNodes();
 
        // take the starting time
        long start = System.currentTimeMillis();
 
        double perc = 0;
 
        // iterate over the vertices of the graph
        NodeIterator iter = graph.nodeIterator();
 
    [COLOR="#FF0000"]    while (iter.hasNext()) [/COLOR]{
 
            // the next node
            int node = iter.next();
 
            // print the percentage of nodes examined so far
            perc = printPerc(node, numNodes, perc);
 
            // fetch the adjacency list of the current "node" by using WebGraph
            // valid positions are those from 0 to outdegree(node)
            int[] succ = iter.successorArray();
 
            // fetch the labels in memory (then discard it)
            String[] labels = labeler.getVertexLabels(succ, 0, iter.outdegree());
 
            // count how many strings have been fetched so far
            counter += labels.length;
        }
 
        // compute the overall elapsed time
        long elapsed = System.currentTimeMillis() - start;
 
        // print some statistics on stdout
        printStats(counter, elapsed);
    }
 
    private static void fetchAttribute(ImmutableGraph graph, GraphLabeler labeler, String attribute) throws IOException {
 
        // count how many labels have been fetched so far
        int counter = 0;
 
        // the total number of nodes in the graph
        int numNodes = graph.numNodes();
 
        // take the starting time
        long start = System.currentTimeMillis();
 
        double perc = 0;
        for (int node = 0; node < numNodes; node++) {
 
            // print the percentage of nodes examined so far
            perc = printPerc(node, numNodes, perc);
 
            // fetch the value of the requested "attribute" for each edge
            // outgoing from "node"
            String[] values = labeler.getOutgoingAttribute(node, attribute);
 
            // count how many labels have been fetched so far
            counter += values.length;
        }
 
        // compute the overall elapsed time
        long elapsed = System.currentTimeMillis() - start;
 
        // print some statistics on stdout
        printStats(counter, elapsed);
    }
 
    private static double printPerc(int node, int numNodes, double percLimit) {
        int perc = (int)(node / (double)numNodes * 100);
        if (perc >= percLimit || node == 0) {
            if (node == 0)
                System.out.print(" >> Progress: ");
            System.out.print(perc + "% ");
            percLimit += 10;
        }
 
        return percLimit;
    }
 
    private static void printStats(int count, long elapsed) {
 
        printPerc(1, 1, 0); // print 100%
 
        int rate = (int)(count / (elapsed / 1000d)); // strings/sec
 
        System.out.println();
        System.out.println(" >> Rate: " + rate + " string/sec");
        System.out.println(" >> Fetched strings: " + count);
        System.out.println(" >> Overall time: " + Utils.elapsedTime(elapsed));
    }
}

cannot find symbol
symbol: method hasNext()
location: variable iter of type NodeIterator. any variable i created not recognize like iter.

please more explain with example