The number is not lost

Question about the task

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Error: "If an empty string is entered after a number, then that number should also be displayed (it must not be lost)." HashMap can work with null key, no?

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.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; 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<>(); while(true) { int id = Integer.parseInt(reader.readLine()); String name = reader.readLine(); if(name.isEmpty()){ map.put(null, id); break; }else map.put(name, id); } for(Map.Entry<String, Integer> pair : map.entrySet()){ String a = pair.getKey(); Integer b = pair.getValue(); System.out.println(a+ " " +b); } } }

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Guadalupe Gagnon

Level 37 , Tampa, United States

9 December 2021, 20:16

The loop should end with any empty input. The way that it is coded above is that it has two reads (lines 21 and 22) before checking if there was an empty input. Also, if an empty input is entered on the line that reads a number a format exception is thrown. So the logic for the reading of the Strings should be: -loop - read a string - check if it is empty - parse that string to a number if it is not empty - or end loop if it is empty - read a second string - check if it is empty - enter both into map if not empty - add number to map and end loop if empty - repeat loop until it ends