MGT

package main;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Random;

public class Main {

    static Random r = new Random();

    public static int readInt() {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n = 0;
        try {
            n = Integer.parseInt(br.readLine());
        } catch (IOException ex) {
            readInt();
        } catch (NumberFormatException ex) {
            System.out.println("Please, enter a digit");
            readInt();
        }
        return n;
    }

    public static int[][] generateGraph(int n) {
        int graph[][] = new int[n][n];
        for (int i=0;i<n;i++)
            for (int j=i;j<n;j++)
                if (i==j)
                    graph[i][j] = 0;
                else
                    graph[i][j] = graph[j][i] = r.nextInt(9);
        return graph;
    }

    public static void printGraph(int[][] graph, int n) {
        for (int i=0;i<n;i++) {
            for (int j=0;j<n;j++)
                System.out.print(graph[i][j]+" ");
            System.out.println();
        }
    }

    public static void main(String[] args) {
        System.out.println("Enter amount of vertexes in graph: ");
        int n = readInt();
        int[][] graph = generateGraph(n);
        printGraph(graph, n);
    }

}