What is wrong

Question about the task

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I'm not sure where I am going wrong, in IntelliJ, I keep getting an out of bounds exception, but I don't think I'm doing anything to or calling index 5(the 6th string in the index), so I'm not sure where this is wrong. Thanks for the help in advance!

package com.codegym.task.task07.task0711; import java.io.BufferedReader; import java.io.InputStreamReader; import java.util.ArrayList; /* Remove and insert */ public class Solution { public static void main(String[] args) throws Exception { BufferedReader r = new BufferedReader(new InputStreamReader(System.in)); ArrayList<String> arr = new ArrayList <String>(); int i =0; String s1 = null; int j = 0; for (i = 0; i < 5; i++) { arr.add(r.readLine()); } { for (j = 0; j < 13; j++) { String s = arr.get(4); arr.add(0, s); arr.remove(4); } { System.out.println(arr.get(i)); } } } }

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Joseph

Level 22 , United States

20 October 2019, 21:27

lines 16, 17, 18 are unnecessary. In 19 and 23 declare the variables like normal inside the for loops. In the second for loop remove first and then add. After the loop print out the list. You could use a for loop like for (String s : arr ) {....}

Patrick freeman

Level 14 , Buffalo, United States

25 October 2019, 19:30

So, when removing the last string in the second for loop, it saves the value for long enough, so that you are able to add it on the next line, similar to cut and paste? Or are all the outputs of the for loop done in parallel? Or another way to word my question, does the computer process the output of the for loop line by line, or all at the same time? Also, this time, I have passed all but one condition, "The program should display the list, each value on a new line". I'm also not sure where I would use the for loop you mentioned(for(String s:arr)). This is my current code:

BufferedReader r = new BufferedReader(new InputStreamReader(System.in));
        ArrayList<String> arr = new ArrayList<String>();

        for (int i = 0; i < 5; i++) {
            arr.add(r.readLine());

            if(i >= 4){
            System.out.println(arr.get(0));
            System.out.println(arr.get(1));
            System.out.println(arr.get(2));
            System.out.println(arr.get(3));
            System.out.println(arr.get(4));}
        }
        {
            for (int j = 0; j < 13; j++) {
                String s = arr.get(4);
                arr.remove(4);
                arr.add(0, s);
            }
        }
    }
}

Joseph

Level 22 , United States

28 October 2019, 04:09

You just have to display the resulting list so it is not necessary to display the list as it was before the removing and the adding. It's true the order is pretty specific. If you want to see the order in which things are done and you're using Intellij you can use the debugging tool. All you have to do is add breakpoints by clicking next to the line number. It will add a red mark or dot. Then right click the code and click debug. The debugger will pop up at the bottom and run the program until it hits a line of code marked by a breakpoint. If you click "Step Over" (second icon over from the console which looks like a broken arrow) it will proceed to the next line in the file. If you click "Step Into" which is one icon over it will take you to the very next line that's executed. You can use an enhanced for loop like this to display the list:

for (String a : arr) {
                System.out.println(a);
            }

You could also display it like this:

for (int i = 0; i < arr.size(); i++) {
                System.out.println(arr.get(i));
            }

You can take out the additional set of curly brackets around the second for loop in line 14 and 20 and display the list right after it. Have each loop be separate from the one before. Hope that helps and keep it up!