Im trying to convert an Int to a boolean for code. Is there a workaround?

Im making a program that takes vertices from a text file and creates a graph. The code takes in a text file with edges, constructs a graph using adjacency list data structure, then finally uses Depth first search (DFS) for searching the graph.

Here is my code:

import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.Scanner;

public class Graph {
    private int V; 
    private ArrayList<Integer>[] adjList; 

    
    public Graph(int V) {
        this.V = V;
        adjList = new ArrayList[V];
        for (int i = 0; i < V; i++) {
            adjList[i] = new ArrayList<Integer>();
        }
    }

    
    public void addEdge(int u, int v) {
        adjList[u].add(v);
    }

    
    public void DFS(int v, boolean[] visited) {
        visited[v] = true;
        System.out.print(v + " ");

        for (int i = 0; i < adjList[v].size(); i++) {
            int neighbor = adjList[v].get(i);
            if (!visited[neighbor]) {
                DFS(neighbor, visited);
            }
        }
    }

    public static void main(String[] args) {
        try {
            Scanner scanner = new Scanner(new File("input.txt"));

            
            int V = scanner.nextInt();
            Graph graph = new Graph(V);

            
            while (scanner.hasNextInt()) {
                int u = scanner.nextInt();
                int v = scanner.nextInt();
                graph.addEdge(u, v);
            }

            
            scanner.close();

            
            for (int i = 0; i < V; i++) {
                System.out.print(i + ": ");
                for (int j = 0; j < graph.adjList[i].size(); j++) {
                    System.out.print(graph.adjList[i].get(j) + " ");
                }
                System.out.println();
            }

            
            Scanner userScanner = new Scanner(System.in);
            System.out.print("Enter starting vertex: ");
            int start = userScanner.nextInt();
            userScanner.close();

            
            boolean[] visited = new boolean[V];
            System.out.println("DFS traversal from vertex " + start + ":");
            graph.DFS(start, visited);

            
            Scanner searchScanner = new Scanner(System.in);
            System.out.print("\nEnter value to search for: ");
            int value = searchScanner.nextInt();
            searchScanner.close();

            
            boolean[] searchVisited = new boolean[V];
            System.out.println("Searching for value " + value + " starting from vertex " + start + ":");
            boolean found = search(graph, start, value, searchVisited);
            if (found) {
                System.out.println("Value " + value + " found in the graph!");
            } else {
                System.out.println("Value " + value + " not found in the graph.");
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }

    
    public static boolean search(Graph graph, int v, int value, boolean[] visited) {
        visited[v] = true;
        if (v == value) {
            return true;
        }

        for (int i = 0;graph.adjList[v].size(); i++) {
               int neighbor = graph.adjList[v].get(i);
               if (!visited[neighbor]) {
                   boolean found = search(graph, neighbor, value, visited);
                   if (found) {
                      return true;
            }
        }
    }

    return false;
}
} 

The error is specifically the for loop in public static boolean search. I get an error saying "Type mismatch: cannot convert from int to boolean" where graph.adjList[v].size() is at.

>Solution :

the problem is in the for loop. the signature of a for is like this

for (statement 1; statement 2; statement 3) {
  // logic
}

where

• statement 1 is executed once
• statement 2 is the condition that decides if the loop must be executed one more time
• statement 3 will be executed after the logic inside the for block is executed

in your case you have

for (int i = 0;graph.adjList[v].size(); i++)

where the statement 2 which is graph.adjList[v].size() is an int. You have to change that and put a condition. Something like

i < graph.adjList[v].size()

or whatever you need