[FIXED] Print message when loop fails

Issue

I am trying to understand why I cannot print my desired outcome. I have changed my loop logic around a few times but cannot see the issue.

I have an array list ArrayList<Landing> landings = new ArrayList<>();

I have the following method in the Landing class to check the landing ID;

public boolean checkId(int id) {
    if (this.landingId == id) {
        return true;

    } else {
        return false;
    }
}

I am trying to create some input handling where if the user inputs an ID which doesn't match an ID in the array list, an error message is printed. I can't seem to get the failed scenario to print the message

System.out.print("Please enter the landing ID: ");
            int id = Integer.parseInt(sc.nextLine());
            boolean unsuccessful = false;
            for (int i = 0; i < landings.size(); i++) {

                if (landings.get(i).checkId(id)) {
                    landings.get(i).printLandings();
                    unsuccessful = false;
                    break;
                } else {
                    unsuccessful = true;

                }
            }

            if (unsuccessful) {
                System.out.println(
                        "\nThe ID you enterred does not match any landing");

            }
break;

TIA

Solution

If you want to check if there's "any" (= at least one) match, you gotta start with boolean unsuccessful = true.

Let's look at the simplest case: When the List is empty, the loop won't run a single time. Though unsuccessful will not be changed and has to set to true before the loop.

Here's a simplified version.

boolean unsuccessful = true
for(...) {
  if(matchFound) {
    unsuccessful = false;
    break;
  }
}

if(unsuccessful) { print(...); }

Maybe you should also consider renaming the variable to success (at least for me that's easier to read):

boolean success = false;
for(...) {
  if(matchFound) {
    success = true;
    break;
  }
}

if(!success) { print(...); }

As you can see, you also don't need the else part anymore.

Answered By - Benjamin M
Answer Checked By - Candace Johnson (JavaFixing Volunteer)