I'm wondering if I can use BufferedReader with both string and integer, and what's wrong with my code?

import java.io.*;

public class Main {
    public static void main(String[] args) {
        int[] nums = {1, 2, 3, 4, 5};
        try {
            var writer = new BufferedWriter(new FileWriter("test.txt"));
            writer.write("hello");
            writer.write("\n welcome");
            for (int num : nums) {
                writer.write(num   "\n");
            }
            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }


        
        try {
            BufferedReader reader = new BufferedReader(new FileReader("test.txt"));
            String line = reader.readLine();
            int num = Integer.parseInt(reader.readLine());
            while (line != null) {
                System.out.println(line);
                line = reader.readLine();
            }
            reader.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

I want to read both int and string that have been written in the above method by JUST using BufferedReader

CodePudding user response：

You can try to check earlier, if given string is a number, e.g.:

private static boolean isNumeric(String str) {
    return str != null && str.matches("[0-9.] ");
}

and then, if isNumeric(line) is true, assign it as integer.

CodePudding user response：

First you are missing a few semicolons(;) on the line where you are creating the nums array and on the line you are writing the string '\n welcome'.

Secondly when writing to you file the first 2 lines are string values, so when you try to use parseInt on the second line it throws a NumberFormatException.