I am not able to satisfy second condition

Question about the task

Under discussion

package com.codegym.task.task07.task0716; import java.util.ArrayList; /* R or L */ public class Solution { public static void main(String[] args) throws Exception { ArrayList<String> list = new ArrayList<String>(); list.add("rose"); // 0 list.add("love"); // 1 list.add("lyre"); // 2 list.add("son"); // 3 list.add("lier"); // 4 list = fix(list); for (String s : list) { System.out.println(s); } } public static ArrayList<String> fix(ArrayList<String> list) { for(int i =0;i<list.size();i++){ if(list.get(i).contains("r") && list.get(i).contains("l")) { continue; }else if(list.get(i).contains("r")){ list.remove(i); } else if(list.get(i).contains("l")) {list.add(i, list.get(i)); i++;} } return list; } }

1. Create a list of words and populate it yourself.
2. The fix method should:
2.1. remove all words containing the letter "r" from the list
2.2. duplicate all words containing the letter "l".
2.3. if a word contains both "r" and "l", then leave it unchanged.
2.4. don't do anything to other words.

For example:
rose lyre love

Output:
lyre love love

Requirements:

The program must not read data from the keyboard.
The fix method should remove all words containing the letter "r" from the list. There is an exception: words containing both "r" and "l" should be left alone.
The fix method must duplicate words containing the letter "l" (add another instance of this word to the list). There is an exception: words containing both "l" and "r" should not be duplicated.
The fix method should not do anything with words that contain both "l" and "r".
The fix method should not do anything with words that don't contain either "l" or "r".

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Kent Hervey Software Engineer/Consult

Expert

16 November 2019, 00:09

I got it to work without making a copy. I did use two independent for loops. first removes; second adds

Gendos

Level 24 , Yekaterinburg, Russia

22 September 2019, 09:48

You cannot just go through the lists and modify them at the same time. When you remove the item from the list, you just skip the next element in it. For example, you have a list of Strings ["Good","OK","Bad","Terrible"] and you want to remove "OK" element from it by using for loop. index for "OK" is 1. and you call list.remove(1). It does remove it from the list and at this time it shifts all elements in the list to fill the hole ["Good","Bad","Terrible"]. So after this, the ineration of the loop continues and i++ call increases your index to 2 - "Terrible", while the "Bad" is left unchecked. For this case, you would need a copy of the list.

public static ArrayList<String> fix(ArrayList<String> list){
        ArrayList<String> copy = new ArrayList<>(list);
        for (int i = 0; i < copy.size(); i++) {
            String element = copy.get(i);
            if(element.contains("r") && element.contains("l")) continue;
            else if(element.contains("r")) list.remove(element);
            else if(element.contains("l")) list.add(element);
        }
        return list;
    }

Antonio

Level 12 , Rotterdam, Netherlands

24 September 2019, 21:01

I have a question why have you made a copy but returned list? I'm not good at this subject can you help me?