Java中的未知编译器错误,我认为这是范围问题

Question

我正在实现广度优先和深度优先搜索类,我在编译时遇到错误,我无法理解.错误是:

symbol:variable aList
location:class java.lang.Object for(graphNode node:map.get(i).aList){

aList变量是一个TreeSet,存储在每个节点中,该节点包含相应图形中节点所连接的节点.我在上面的main方法中使用完全相同的语法,它不会给出任何错误.此外,当我在遍历方法中打印出地图中的所有节点时,它会打印整数键,而不是它应该具有的graphNode值.我现在很困惑.谢谢你的帮助.

import java.util.*;
import java.io.*;


public class HW1 {

public static void main (String[] args) throws Exception {
    Scanner sc = new Scanner(new File(args[0]));
    sc.useDelimiter("(\\s)"); // divide up by whitespcae

    TreeMap<Integer, graphNode> map = new TreeMap<Integer, graphNode>();
    int totalNodes = Integer.parseInt(sc.next());
    int totalEdges = Integer.parseInt(sc.next());

    // Fill up the map with nodes
    for(int i = 1; i <= totalNodes ; i++) {
        map.put(i, new graphNode(i, null, 10000));

    }

   // Add all the edges to the adjacency list
    while(sc.hasNext()){
        int start = Integer.parseInt(sc.next());
        int end = Integer.parseInt(sc.next());
         graphNode startNode = map.get(start);
         graphNode endNode = map.get(end);

         if(!startNode.aList.contains(endNode)){
            startNode.aList.add(endNode);
         }
         if(!endNode.aList.contains(startNode)){
            endNode.aList.add(startNode); 
        }
    }

    for(int i = 1; i <= map.size(); i++){
        for(graphNode node: map.get(i).aList){
            System.out.print(node.value+" ");
        }
        System.out.println("");
    } 

    traverse(map);

}

public static void traverse(TreeMap map){

        for(int i = 1; i <= map.size(); i++){
            for(graphNode node: map.get(i).aList){
                System.out.print(node.value+" ");
            }
            System.out.println("");
        } 

}

}
import java.util.*;
import java.io.*;

public class graphNode implements Comparable<graphNode> {
int value;
int distance;
graphNode prev;
TreeSet<graphNode> aList;
String color;


public graphNode(int value, graphNode prev, int distance) {
    this.value = value;
    this.prev = prev;
    this.distance = distance;
    aList = new TreeSet<graphNode>();
    String color = "white";
}

public String toString() {
    return value + "";
}

public int compareTo(graphNode other) {
    if (this.value < other.value){
        return -1;
    }else if (this.value == other.value){
        return 0;
    }else{
        return 1;
    }
}

}

Answer 1

在main,map是一个

TreeMap<Integer, graphNode> map = new TreeMap<Integer, graphNode>();

但在traverse,它只是一个TreeMap.所以get(i)返回一个Object,而不是一个graphNode.

一个Object没有aList场.

宣布

public static void traverse(TreeMap<Integer, graphNode> map){