details error

Question about the task

We don't need repeats

Java Syntax, Level 8, Lesson 8

Under discussion

I don't know if there's something wrong with it,if it has,plz help me thx.need specific details very appreciate

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; import java.util.Iterator; /* We don't need repeats */ public class Solution { public static HashMap<String, String> createMap() { //write your code here HashMap<String,String> hashmap = new HashMap<String,String>(); hashmap.put("leo" , "leo"); hashmap.put("wo" , "woshi"); hashmap.put("wori" , "wori"); hashmap.put("woshishui" , "wobushi"); hashmap.put("wohendiao" , "wohendiao"); hashmap.put("wob" , "woc"); hashmap.put("nihao" , "nibuhao"); hashmap.put("woshita" , "woshita"); hashmap.put("shui" , "woniu"); hashmap.put("hao" , "hao"); return hashmap; } public static void removeFirstNameDuplicates(Map<String, String> map) { //write your code here int count = 1; Map<String, String> helper = new HashMap<String,String>(); Iterator<Map.Entry<String,String>> iterator = map.entrySet().iterator(); while(iterator.hasNext()){ Map.Entry<String,String> pair = iterator.next(); String key = pair.getKey(); String value = String.valueOf(count); helper.put(key,value); if(map.containsKey("key")){ count++; } } Iterator<Map.Entry<String,String>> iterator1 = helper.entrySet().iterator(); while(iterator.hasNext()){ Map.Entry<String,String> pair = iterator1.next(); String key = pair.getKey(); String value = pair.getValue(); if(Integer.parseInt(value) >1){ removeItemFromMapByValue(helper,value); } } } 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

11 November 2020, 14:52

Your code doesn't work but I don't know what your intentions are. If you want help you are going to need to comment your code to explain what you are attempting to do so we can provide you with assistance. Here is what the code does do: In the remove first names method it looks like the code adds every entry into the helper list (line 38) then tries to count, starting at one, how many times the literal string "key" is contained in the key set of the map (line 39), which typically ends up being none, but wont matter anyways because the variable count is never used. Then the code creates another loop at line 43 to loop throw the helper map, which is just a copy of the original map, and tries to parse each first name into an integer (line 48), which wont be greater than 1 but instead throw a number format exception and crash the code.

Guanting Liu

Level 16 , Springfield, United States

11 November 2020, 14:59

ok,so the duplicate search is not correct,so what's the idea to do this with calling the method below?If it is not a map instead of an array,I don't think I can have a clear mind about how to do the samething either.

Guadalupe Gagnon

Level 37 , Tampa, United States

11 November 2020, 15:09

I don't see any search in the code above. The only thing sort of like a search is line 39, but that is trying to search for a hard coded string "key".... not the variable key. "key" ---> key Notice the quotation marks surrounding a string. Also, count is never used. What is your intention with it? Maybe to create a new list that counts each time a first name appears more than once? That would be a list of (String, Integer) and not (String, String). The contains() method is not the proper way to do that either as it will be true 100% for each name because the map would contain the name if you got the name from the map in the first place.

Guanting Liu

Level 16 , Springfield, United States

11 November 2020, 15:24

I am also confused about my code,so I will post my understanding about this task here,the task is to ask 1.to create a map with 10 pair <String,String>. 2.to check if there are duplicate first name,that value is a string which could be reached using getValue() method. 3.to call method(map,value) which is a method to check if the value is matched,remove the pair. That's my idea,I think there are some confusions especially how to use the removeItemFromMapByValue on the RemoveFirstNameDuplicate Method for sure.

Guadalupe Gagnon

Level 37 , Tampa, United States

11 November 2020, 15:38

1. Yes 2. Yes 3. ... maybe 3 should be to check each value in the map to see that it is only contained once. If it is contained more than once then to remove all of them. For each value to remove you have to remove it by calling removeItemFromMapByValue() passing in the map and the name to be removed. That method will remove every single occurrence of the name passed to it in the map.