Why 2 last requirerements don't met

Question about the task

We don't need repeats

Java Syntax, Level 8, Lesson 8

Resolved

I think everything is fine

Create a Map<String, String> and add ten entries that represent (last name, first name) pairs.
Remove people with the same first name.

Requirements:

The program should not display text on the screen.
The program should not read values from the keyboard.
The createMap() method must create and return a HashMap that has (String, String) elements and contains 10 entries.
The removeFirstNameDuplicates() method must remove from the map all people who have the same first name.
The removeFirstNameDuplicates() method must call the removeItemFromMapByValue() method.

package com.codegym.task.task08.task0817; import java.util.HashMap; import java.util.Map; /* We don't need repeats */ public class Solution { public static HashMap<String, String> createMap() { HashMap<String,String> cr_Map = new HashMap<>(); cr_Map.put("Alex1", "Adamchuk"); cr_Map.put("Max2", "Raitin"); cr_Map.put("Alex3", "Adamchuk1"); cr_Map.put("Max4", "Raitin"); cr_Map.put("Kostya5", "Fedichkin"); cr_Map.put("Kostya6", "Fedichkin"); cr_Map.put("Oleg7", "Visotsky"); cr_Map.put("Aba88", "Duba"); cr_Map.put("Eugene9", "Alex"); cr_Map.put("Raitin10", "Max"); return cr_Map; } public static void removeFirstNameDuplicates(Map<String, String> map) { //write your code here HashMap<String,String> cr_Map1= new HashMap<>(map); for(Map.Entry<String,String> x : cr_Map1.entrySet()) { int count = 0; for (Map.Entry<String, String> y : map.entrySet()) { if (y.getValue().equals(x)) count++; } if (count > 1) { removeItemFromMapByValue(map, x.getKey()); } } } public static void removeItemFromMapByValue(Map<String, String> map, String value) { HashMap<String, String> copy = new HashMap<>(map); for (Map.Entry<String, String> pair : copy.entrySet()) { if (pair.getValue().equals(value)) map.remove(pair.getKey()); } } public static void main(String[] args) { } }

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Gellert Varga

Level 23 , Szekesfehervar, Hungary

7 March 2021, 21:52

solution

1) Paste this code into the main () method, run the program and see what it does.

HashMap<String,String> hshm = createMap();
System.out.println(hshm);
removeFirstNameDuplicates(hshm);
System.out.println(hshm);

2) Line 33: "equals(x)" - this should be rethought. y.getValue() - you use the getValue() on the y. And on the x? 3) Line 36: "x.getKey()" - this should be rethought. Think of the name of the method: removeItemFromMapByValue() , so: by value, not by key.

Maxim Raitin

Level 20 , Tomsk, Russian Federation

8 March 2021, 11:52

Thank you a lot man! I've done so stupid mistakes..

Gellert Varga

Level 23 , Szekesfehervar, Hungary

8 March 2021, 17:28

You're welcome. We all do that sometimes. If you test your program often, then the bug will be out:)

Nouser

Level 36 , Germany

7 March 2021, 21:46

have you tested your code?

public static void main(String[] args) {
    Map<String, String> map = createMap();
    removeFirstNameDuplicates(map);
    map.entrySet().forEach(p -> System.out.println(p.getKey() + " - " + p.getValue()));
}

The Fedichkins seem still to be there