Does not print out the right words

Question about the task

R or L

Java Syntax, Level 7, Lesson 9

Resolved

Tried several different variations of the code and I can never get the list.add line to duplicate the word.

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".

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 = 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++) { String s = list.get(i); if (s.contains("l") && (s.contains("r"))) { continue; } if (s.contains("l") && !(s.contains("r"))) { list.add(s); } else if (s.contains("r") && !(s.contains("l"))) { list.remove(s); } } return list; } }

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Gellert Varga

Level 23 , Szekesfehervar, Hungary

26 June 2020, 15:35

solution

1) In the case of list.remove() : you need to set back the variable "i" with -1. The item of the list in the same given index is going tho have a new item (the earlier next item) (and not an empty hole). So the same index need a checking again. But the head of the loop increase the variable "i" with +1, so you need it manually decrease with -1. 2) Your loop in this form results an endless loop. I tried the program with this list:

list.add("rose");
list.add("love");
list.add("lizi");

and add the

System.out.println(list.get(i));

command between the line 33 and 34. The output will be: love lizi lizi ... and so forth, "lizi" for endless many times. Similar situation like at the point 1. You add a new item to the list, and in the next circle you're checking this new item (but this is the same), and thus you add it again. In the next circle again. And so forth. Don't add this item to the end of the list:

list.add(s);

but add it to the next index:

list.add(i+1, s);

and increase the "i" with extra +1 manually to skip checking this item in the next circle.