Passing a filename as a argument in Java

October 8, 2023

i started learning java for a couse in my university. Im having a bit of problems on this challenge. I want to pass the filename lets say num.txt as a argument (javac Ex1.java "filename"). Then use that file to do some operations. The code right now is as such:

import java.io.*;
import java.net.URI;
import java.util.*;
import java.nio.file.*;
import java.nio.charset.*;

public class Ex1{
    public static void main(String[] args){
    

    try{
        Charset ENCODING = StandardCharsets.UTF_8;
        Path path = Paths.get("num.txt");
        List<String> linhas = Files.readAllLines(path,ENCODING);
        for(int i=0;i<linhas.size();i++){
            System.err.println("Linhas n" + i+":"+linhas.get(i));
        }
        int num1 = Integer.parseInt(linhas.get(0));
        int num2 = Integer.parseInt(linhas.get(1));
        System.out.println(num1+num2);
        System.out.println(num1-num2);
        System.out.println(num1*num2);
        System.out.println(num1/num2);
        

    }catch(IOException ex){
        System.out.println("Erro!");
    }
}
}

I would like some documentation or help. Thanks in advance.