For loop failing in my code. Not executing at all

Question

I am trying to execute following code and found that for loop is not executing at all. Even not getting any error. Let me clear that "dateList" is a list of string and it's not empty, I already tried printing that. "monthList" is an ArrayList of string.

private ArrayList<String> monthList = new ArrayList<String>(Arrays.asList("Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"));
private List<String> dateList = new ArrayList<>();
private List<Date> finalDatesInMMMDDYYYYFormate = new ArrayList<>();
private int year = 2019;



 for (int m=0; m<dateList.size(); m++){
        System.out.println("Date at position ------ "+m+" is -------"+dateList.get(m));
    } // length of this list is 9 & it prints eberything from 0 to 9. It is not empty.
    int assignYear = year;
    for (int k=1; k<dateList.size(); k++){
        if (dateList.get(k).substring(0,2)==dateList.get(k-1).substring(0,2) || dateList.get(k).substring(0,2) == monthList.get(0)){
            finalDatesInMMMDDYYYYFormate.add(Utils.parseDate(dateList.get(k)+Integer.toString(assignYear).replaceAll("[^a-zA-Z0-9]",""), new SimpleDateFormat("MMMddyyyy")));
        }
        else if (dateList.get(k).substring(0,2) == monthList.get(11)){
            finalDatesInMMMDDYYYYFormate.add(Utils.parseDate(dateList.get(k)+Integer.toString(assignYear-1).replaceAll("[^a-zA-Z0-9]",""), new SimpleDateFormat("MMMddyyyy")));
            assignYear = assignYear-1;
        }
        else {
            for (int l=0; l<monthList.indexOf(dateList.get(k-1).substring(0,2)); l++){
                if (dateList.get(k).substring(0,2) == monthList.get(l)){
                    finalDatesInMMMDDYYYYFormate.add(Utils.parseDate(dateList.get(k)+Integer.toString(assignYear).replaceAll("[^a-zA-Z0-9]",""), new SimpleDateFormat("MMMddyyyy")));
                    break;
                }
                else {
                    finalDatesInMMMDDYYYYFormate.add(Utils.parseDate(dateList.get(k)+Integer.toString(assignYear-1).replaceAll("[^a-zA-Z0-9]",""), new SimpleDateFormat("MMMddyyyy")));
                    assignYear--;
                    break;
                }
            }
        }
    }

Questions seeking debugging help (*"Why isn't this code working?"*) must include the desired behavior, a specific problem or error and the shortest code necessary to reproduce it in the question itself. Questions without a clear problem statement are not useful to other readers. See [ask]. — RaminS, Feb 13 '19 at 19:21
@PM77-1 as you can see in code, I commented that list is not empty at all. I printed that in console and it returning all 9 values. — Jigar Patel, Feb 13 '19 at 20:24
@M.Goodman The main for is not executing which is start from "for (int k=1; k — Jigar Patel, Feb 13 '19 at 20:25
Run it step-by-step under debugger and you can see all the interim values. — PM 77-1, Feb 13 '19 at 20:33
@M.Goodman Because after that for loop I am printing size of "finalDatesInMMMDDYYYYFormate" which is showing it has no values. — Jigar Patel, Feb 13 '19 at 20:47
@PM77-1 Sure I will try that. But do you think I am doing any mistake within for loop?? — Jigar Patel, Feb 13 '19 at 20:48
The issue is definitely in adding items to the list, not the for loops if everything you've said is accurate. You can verify if the for loop is being entered with the debugger or by printing a value in each code block to identify where your code is going and if it's parsing correctly. — M. Goodman, Feb 13 '19 at 20:57
If the code you wrote does not behave the way you intended then you must have a mistake. — PM 77-1, Feb 13 '19 at 21:03
@M.Goodman I try debugging that. Showing that value of k is incrementing with every loop. That means I made some mistake adding the values into the list. Is it so?? Any idea or suggestion?? — Jigar Patel, Feb 13 '19 at 21:10
Finally I see it. You are comparing strings with `==`. Use `equals()` method instead. — PM 77-1, Feb 13 '19 at 21:12
PM-77 is correct. Strings are objects. Use .equals() for Strings. — M. Goodman, Feb 13 '19 at 21:16

score 1 · Answer 1 · answered Feb 13 '19 at 19:25

1

You appear to never be adding anything to dateList, so it's empty when you start the loop. Thus there's nothing to loop over.

answered Feb 13 '19 at 19:25

Jordan

2,273
9
16

I already added to dateList and it has size 9. checked that by printing all values. It's not empty at all. – Jigar Patel Feb 13 '19 at 19:28

M. Goodman · Answer 2 · 2019-02-13T20:03:21.690

0

dateList has nothing added to it. Its size is therefore 0. As m is then equal to dateList.size() the for loop doesn't execute.

edited Feb 13 '19 at 20:03

answered Feb 13 '19 at 19:24

M. Goodman

141
9

I already added to dateList and it has size 9. checked that by printing all values. – Jigar Patel Feb 13 '19 at 19:27
In the code posted dateList is declared directly before the for loop. The dateList in this code block has nothing in it. If this is the way it is written in your program the size of the dateList when the for loop is evaluated is 0. – M. Goodman Feb 13 '19 at 19:29

For loop failing in my code. Not executing at all

2 Answers2