How do I solve the exception in thread main? what is going wrong?

Question

I tried to write a small program, but it keeps getting an arror message:

Exception in thread "main" java.lang.NumberFormatException: For input string: "hallo"
    at java.lang.NumberFormatException.forInputString(Unknown Source)
    at java.lang.Integer.parseInt(Unknown Source)
    at java.lang.Integer.parseInt(Unknown Source)
    at TheNoteBook.main(TheNoteBook.java:7)

I really don't understand what is going on. I use Eclipse.

import java.util.Scanner;
public class TheNoteBook {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);

        int t = Integer.parseInt( in.nextLine() );
        for(int c=0; c<t; c++){
            String word = in.nextLine();
            Note note = new Note(word);
            System.out.println("Note " +c+ " says: " + note.getContent() ); 


       }

    }

Answer 1

Your code works fine. You are just giving the program the wrong input.

NumberFormatException means, you are trying to convert something to a number that is no number. In your case, you tried to convert hallo to a number.

So you are trying to parse an integer, but your input is a String hallo. How is your class supposed to convert hallo to a number? So you probably tried entering a String first, while your very first input must be a number.

By the way, you should use the nextInt() method to get a number input rather than nextLine().

Scanner in = new Scanner(System.in);

        int t = in.nextInt();
        in.nextLine();
        for (int c = 0; c < t; c++)
        {
            String word = in.nextLine();
            Note note = new Note(word);
            System.out.println("Note " + c + " says: " + note.getContent());
        }