guys i m tired trying.

Question about the task

We don't need repeats

Java Syntax, Level 8, Lesson 8

Resolved

i couldn't figure out. where i go wrong. someone plis help me out. thank you

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; public class Solution{ public static HashMap<String, String> createMap(){ HashMap<String, String> map = new HashMap<String, String>(); map.put("haokip1", "stephen0"); map.put("haokip2", "stephen9"); map.put("haokip3", "stephen8"); map.put("haokip4", "stephen7"); map.put("haokip5", "stephen6"); map.put("haokip6", "stephen5"); map.put("haokip7", "stephen4"); map.put("haokip8", "stephen3"); map.put("haokip9", "stephen4"); map.put("haokip0", "stephen2"); return map; } public static void removeFirstNameDuplicates(Map<String, String> map){ int count = 0; HashMap<String, String> copy = new HashMap<String, String>(map); for(Map.Entry<String, String>pair1 : map.entrySet()){ String first = pair1.getValue(); for(Map.Entry<String, String>pair2 : copy.entrySet()){ String second = pair2.getValue(); if(second.equals(first)){ count++; } if(count>=2){ //map.remove(pair1.getValue()); removeItemFromMapByValue(map, first); } count = 0; } } } public static void removeItemFromMapByValue(Map<String, String> map, String value){ HashMap<String, String> copy = new HashMap<String, String>(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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Stephen Haokip

Level 12 , imphal, India

17 August 2020, 15:47

thank you everyone i manage to solve it

Misiu

Level 41 , Gdansk, Poland

17 August 2020, 15:30

Delete "count" variable. Create copy2 of map. In line 29 change "map" into "copy2". In line 35 use condition like this: if ([the same values] but not [the same keys]) removeItemFromMapByValue(map,[duplicated value]);

Stephen Haokip

Level 12 , imphal, India

17 August 2020, 15:00

please somebody.. tell me what to delete from my code.. and what to add

Misiu

Level 41 , Gdansk, Poland

17 August 2020, 13:47

Iterate on two copies of map, not the map itself. Condition for removing element: if ([the same values] but not [the same keys])

dhanush

Level 30 , Chennai, India

17 August 2020, 13:14

Acutally i don't know why are you iterating the hash map for two time line 30 and 33 Get rid of line 30 you create a map and pass the map as argument which is returned from the createMap method if you create two HashMap with the same name means it ends with an error concurrentmodificationexception. And the current code,It doesn't delete any element from the map do the following steps as BuleJavaBanana.

Misiu

Level 41 , Gdansk, Poland

17 August 2020, 13:03

If duplicated values aren't one just after another then count never will be >=2.

Stephen Haokip

Level 12 , imphal, India

17 August 2020, 12:39

please look at my solution. please point out the mistake.

BlueJavaBanana

Level 37

17 August 2020, 12:36

In the removeFirstNameDuplicates method 1. Make a new List<String> 2. Use this list to store the KEY of any duplicate names. 3. One you have looped through the HashMap and found all the duplicate then loop through the List and remove all the names from the hashmap that have the KEY from your List. Does that make sense?