Problem with thrid condition

Question about the task

Under discussion

Output is correct. Can't understand where is the problem. Output of the program (if were inserted numbers as strings). 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10

1. Read 10 words from the keyboard and add them to a list of strings.

2. The doubleValues method should duplicate words like this:
alpha, beta, gamma, -> alpha, alpha, beta, beta, gamma, gamma.

3. Display the result, each value on a new line.

Requirements:

Declare a string list variable and immediately initialize it.
Read 10 lines from the keyboard and add them to the list.
The doubleValues method should duplicate list elements like this: alpha, beta, gamma, -> alpha, alpha, beta, beta, gamma, gamma.
Display the resulting list, each element on a new line.

package com.codegym.task.task07.task0717; import java.io.BufferedReader; import java.io.InputStreamReader; import java.util.ArrayList; /* Duplicating words */ public class Solution { public static void main(String[] args) throws Exception { BufferedReader reader = new BufferedReader (new InputStreamReader (System.in) ); ArrayList<String> list = new ArrayList<String>(); for (int i = 0 ; i < 10 ; i++) list.add(reader.readLine()); doubleValues(list); for (int i = 0 ; i < list.size() ; i++) System.out.println( list.get(i) ); } public static void doubleValues(ArrayList<String> list) { int position = 0; boolean checkEnd = false; String buffer = null; while (!checkEnd) { buffer = list.get(position); list.add(position + 1, buffer); position += 2; if (position > list.size() - 1) checkEnd = true; } } }

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Guadalupe Gagnon

Level 37 , Tampa, United States

2 May 2019, 19:44

What Steven is saying is that the starting code for this task was:

public class Solution {
    public static void main(String[] args) throws Exception {
        // Read strings from the console and declare an ArrayList here

        ArrayList<String> result = doubleValues(list);

        // Display result
    }

    public static ArrayList<String> doubleValues(ArrayList<String> list) {
        //write your code here
        return null;
    }
}

It looks like you changed the return type of the doublesValues method. This is most likely the reason that you are failing the task. Reset the task, then you can copy and paste the code that you wrote into the task without changing the code already there. You will need to modify a few lines (see Stevens reply) to work with the doublesValues method correctly using its return value.

Steven Mcilhone

Level 17 , Belfast, United Kingdom

2 May 2019, 18:38

line 20 back to

ArrayList<String> result = doubleValues(list);

line 22-24 use an enchaged for loop

for (String x : result){
                System.out.println(x);
            }

then

public static ArrayList<String> doubleValues(ArrayList<String> list) {
              //loop array
      		for(int i = 0; i < list.size();) {
      		    //check out of bounds
       	  	if(i<list.size()-1) {
       	  	    //add copy to array
       	  		list.add(i, list.get(i));
       	  		//skip copy so it doesnt clone it
       	  		i = i + 2;
       	  	}else {
       	  	    //this only runs if its the last element stopping the loop
       	  		list.add(i, list.get(i));
       	  		break;
       	  	}

      		}
          return list;
      }

Guadalupe Gagnon

Level 37 , Tampa, United States

2 May 2019, 19:42

this is all that is needed:

public static void doubleValues(ArrayList<String> list) {
   for (int i = 0; i < list.size(); i += 2)
      list.add(i + 1, list.get(i));
   return list;
}

your if else block is superfluous because there is a check already in the for loop initialization that says it will only run if i is less than list.size.

Phil Patterson

Level 11 , Chisinau, Moldova, Republic of

4 May 2019, 08:00

Thanks a lot, it helped.