I get an error when nothing is entered for id.

Question about the task

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I've spent hours on this and I don't know what more to do. The code works just fine if nothing is entered for name, but I get a NumberFormatException error when nothing is entered for id.

Task: The program reads a pair (a number and string) from the keyboard and displays it on the screen.
New task: The program reads pairs (a number and string) from the keyboard and stores them in a HashMap.
Any empty input signifies the end of data entry.
The numbers can be repeated.
The strings are always unique.
The entered data must not be lost!
The program then displays the contents of the HashMap on the screen.
Each pair on a new line.

Example input:
1 Sam 2 I 1 Am

Example output:
1 Sam 2 I 1 Am

Requirements:

The program must read data from the keyboard.
The program should display text on the screen.
In the main method, declare a HashMap variable and immediately initialize it.
The program should put the pairs read from the keyboard into the HashMap.
The program should display the contents of the HashMap in accordance with the conditions. The key and value are separated by a space. Each value should be on a new line.

package com.codegym.task.task10.task1019; import java.io.*; import java.util.HashMap; import java.util.Map; /* Functionality is not enough! */ public class Solution { public static void main(String[] args) throws IOException { BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); HashMap<String, Integer> map = new HashMap(); String name; Integer id; for (;;) { id = Integer.parseInt(reader.readLine()); name = reader.readLine(); map.put(name, id); if (name.isEmpty() || id == null) { break; } } for (Map.Entry<String, Integer> pair : map.entrySet()) { name = pair.getKey(); id = pair.getValue(); System.out.println(id+ " " + name); } } }

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Gellert Varga

Level 23 , Szekesfehervar, Hungary

23 April 2021, 14:52

Second part. Line 22: The input may have read null or an empty string. Therefore, this should not be sent immediately to the Integer.parseInt() method because both of them are impossible to convert to integer. = Exception ("error").

Gellert Varga

Level 23 , Szekesfehervar, Hungary

23 April 2021, 14:47

Before you use the Integer.parseInt() method, and before you put anything into the map, you have to check: if (inputString==null || inputString.isEmpty()) break; if (inputString.isEmpty() || inputString==null ) break; // this is wrong order. If the prg reads 'null' and puts it into 'inputString' variable, and you try to call the isEmpty() method on this 'null' then you will get an NullpointerException. But if the first check is this: inputString==null , then it will be true, and JVM already will not check the second condition (.isEmpty), because the whole condition is true surely (this is how works the logical OR operation). So you won't get NullpointerException.