关于 BFS 算法的困惑

Question

The following code is used to traverse a graph and print the elements in vertices ... but this code is suitable if the elements are numbers .... suppose that these elements are string or characters ... what changes can I do to print string or characters

import java.io.*; 
import java.util.*; 
  
// This class represents a directed graph using adjacency list 
// representation 
class Graph 
{ 
    private int V;   // No. of vertices 
    private LinkedList<Integer> adj[]; //Adjacency Lists 
  
    // Constructor 
    Graph(int v) 
    { 
        V = v; 
        adj = new LinkedList[v]; 
        for (int i=0; i<v; ++i) 
            adj[i] = new LinkedList(); 
    } 
  
    // Function to add an edge into the graph 
    void addEdge(int v,int w) 
    { 
        adj[v].add(w); 
    } 
  
    // prints BFS traversal from a given source s 
    void BFS(int s) 
    { 
        // Mark all the vertices as not visited(By default 
        // set as false) 
        boolean visited[] = new boolean[V]; 
  
        // Create a queue for BFS 
        LinkedList<Integer> queue = new LinkedList<Integer>(); 
  
        // Mark the current node as visited and enqueue it 
        visited[s]=true; 
        queue.add(s); 
  
        while (queue.size() != 0) 
        { 
            // Dequeue a vertex from queue and print it 
            s = queue.poll(); 
            System.out.print(s+" "); 
  
            // Get all adjacent vertices of the dequeued vertex s 
            // If a adjacent has not been visited, then mark it 
            // visited and enqueue it 
            Iterator<Integer> i = adj[s].listIterator(); 
            while (i.hasNext()) 
            { 
                int n = i.next(); 
                if (!visited[n]) 
                { 
                    visited[n] = true; 
                    queue.add(n); 
                } 
            } 
        } 
    } 

Answer 1

Like Szprota21 says you need to incorporate generics into your Graph class:

class Graph<T> 
{ 
    private int V;   // No. of vertices 
    private LinkedList<T> adj[]; //Adjacency Lists 
  
    // Constructor 
    Graph(int v) 
    { 
        V = v; 
        adj = new LinkedList<T>[]; 
        for (int i=0; i<v; ++i) 
            adj[i] = new LinkedList<T>(); 
    } 

    // Continue using T

Which allows you to use:

Graph<Integer> intgraph = new Graph<Integer>(5);
Graph<String> intgraph = new Graph<String>(5);
Graph<Character> intgraph = new Graph<Character>(5);

And just like previously mentioned use:

T value = queue.poll();
value.toString();