I don't understand what's wrong this time

Question about the task

Under discussion

So I've made it so I'm not removing from the loop I'm iterating through in addition to adding a nested loop that removes if the string is the same. How would I go about fixing this? I believe I'm on my 10th or so attempt.

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.Iterator; import java.util.Map; /* We don't need repeats */ public class Solution { public static HashMap<String, String> createMap() { //write your code here HashMap<String, String> names = new HashMap<String, String>(); names.put("Smith", "John"); names.put("Sorel", "Ani"); names.put("Kiributa", "COD"); names.put("James", "Jesse"); names.put("RS", "Settled"); names.put("Sorni", "Pilia"); names.put("Gono", "Forsen"); names.put("Anime", "Jesse"); names.put("Fun", "Spongebob"); names.put("MOD", "COD"); return names; } public static void removeFirstNameDuplicates(Map<String, String> map) { //write your code here HashMap<String, String> newMap = new HashMap<String, String>(map); Iterator<Map.Entry<String, String>> iter = newMap.entrySet().iterator(); while(iter.hasNext()){ Map.Entry<String, String> entry = iter.next(); String s = entry.getValue(); while(iter.hasNext()){ Map.Entry<String, String> oNext = iter.next(); String n = oNext.getValue(); if(s.equals(n)){ removeItemFromMapByValue(map, s); } } } } 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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Guadalupe Gagnon

Level 37 , Tampa, United States

7 November 2019, 16:07

The removeFirstNameDuplicates() isn't checking every value for duplicates. Every time .next() is called on the iterator it moves it moves the iterations along by 1. So at line 35 you set a value to be a base to check against other values, then create an inner loop at line 37 to do this. When a duplicate is found then it removes it from map. Problem: take for example these for values {tom, jerry, jerry, tom} because they are both duplicates, they should all be removed. Here is what happens: line 35-36: next is called and moves to index 0 and sets the value of s to tom line 37-43: (looping) inner loop next is called moving index to 1, jerry doesn't match tom inner loop next is called moving index to 2, jerry doesn't match tom inner loop next is called moving index to 3, tom matches tom and this value is removed hasnext() at line 34 returns false because the index is at 3 which is the max and the method ends. In this example both 'jerry' values remain in map. This needs to be fixed.