CodeGym/Help with Java Tasks/Not verifying

Level 30

London

26.11.2019
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11comments

Not verifying

Question about the task

Resolved

The mentor recommendation is: If an empty string is entered after a number, then that number should also be displayed (it must not be lost). Except it is currently doing that. I entered: 1 a 2 b 3 c 4 And the output was: 1 a 2 b 3 c 4

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; /* Functionality is not enough! */ public class Solution { public static void main(String[] args) throws IOException { BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); HashMap<Integer, String> map = new HashMap<>(); while(true) { String s = reader.readLine(); if(s.equals("")) { //or s.isEmpty() break; } int id = Integer.parseInt(s); String name = reader.readLine(); if (name.equals("")){//or name.isEmpty() map.put(id, ""); break; } map.put(id,name); } for (HashMap.Entry<Integer, String> pair : map.entrySet()){ Integer key = pair.getKey(); String value = pair.getValue(); System.out.println(key + " " + value); } } }

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Guadalupe Gagnon

Level 37 , Tampa, United States

26 November 2019, 17:10

try this:

while(true) {
   String s = reader.readLine();

   if(s.equals("") || s == null) { //or s.isEmpty()
      break;
   }

   int id = Integer.parseInt(s);

   String name = reader.readLine();

   map.put(id,name);

   if(name.equals("") || name == null) break;
}

Anthony Chalk

Level 30 , London, United Kingdom

26 November 2019, 17:57

I changed my code to:

while(true) {
    String s = reader.readLine();

    if(s.equals("")|| s == null) {
        break;
    }

    int id = Integer.parseInt(s);

    String name = reader.readLine();
    map.put(id,name);

    if (name.equals("")|| name == null){
        break;
    }
}

Still not validating (for the same reason))

Guadalupe Gagnon

Level 37 , Tampa, United States

26 November 2019, 18:15

Try reversing the null check in each if statement. That was poor programming on my part. If the String is null then calling .equals() will throw a null pointer exception:

if(s == null || s.equals(""))

Also, and this may seem silly but try moving

map.put(id,name);

until after the

if ( name == null || name.equals(""))
  break;

Anthony Chalk

Level 30 , London, United Kingdom

26 November 2019, 18:23

while(true) {
    String s = reader.readLine();

    if(s == null|| s.equals("")) {
        break;
    }

    int id = Integer.parseInt(s);

    String name = reader.readLine();

    if (name == null||name.equals("") ){
        break;
    }
    map.put(id,name);
}

Same result

Guadalupe Gagnon

Level 37 , Tampa, United States

26 November 2019, 18:42

https://codegym.cc/help/5113 Scroll to the bottom. A couple people posted their solution that passed.

Guadalupe Gagnon

Level 37 , Tampa, United States

26 November 2019, 18:43

BLah....... I'm dumb. Your map is set up incorrectly. Numbers can be repeated while names cannot. That means that the map should be [String, Integer] not [Integer, String]....

Anthony Chalk

Level 30 , London, United Kingdom

26 November 2019, 19:27

New code

HashMap<String, Integer> map = new HashMap<>();

     while(true) {
         String name = reader.readLine();

         if (name == null||name.equals("") ){
             break;
         }
         String s = reader.readLine();
         Integer id = Integer.parseInt(s);

         if(s == null|| s.equals("")) {
             break;
         }
         map.put(name,id);


     }

     for (HashMap.Entry<String, Integer> pair : map.entrySet()){
         String key = pair.getKey();
         Integer value = pair.getValue();
         System.out.println(value + " " + key);
     }

now the second and last condition are failing, with the recommendation: You've mixed up the order of the output.

Guadalupe Gagnon

Level 37 , Tampa, United States

26 November 2019, 19:44

solution

you are supposed to read a number and then a name, that part was correct from your old code. The only issue was the map. Fix the while loop so that the number is entered first followed by the name.

Anthony Chalk

Level 30 , London, United Kingdom

26 November 2019, 20:12

Thank you, finally works

Guadalupe Gagnon

Level 37 , Tampa, United States

26 November 2019, 20:18

88 88 88 88,dPPYba, 88 88 8b,dPPYba, 8b,dPPYba, ,adPPYYba, 8b d8 88P' "8a 88 88 88P' "Y8 88P' "Y8 "" `Y8 `8b d8' 88 88 88 88 88 88 ,adPPPPP88 `8b d8' 88 88 "8a, ,a88 88 88 88, ,88 `8b,d8' 88 88 `"YbbdP'Y8 88 88 `"8bbdP"Y8 Y88' d8' d8'

Mateusz haszyaz

Level 12 , Wroclaw, Poand

21 December 2019, 20:13

Thanks you guy. I had the same problem with my HashMap.