Htykuut

I am receiving below error, when I try to set value on a JProgressBar.

"Optional cannot be converted to Int"

Could someone please advise any workarounds/Solution??

public GUI(){

    initComponents();

    tL = new TasksToDo();

    jProgressBar1.setValue(tL.retrieveTotalHours());// [Where my error occurs]}

}  

And from the TaskToDo Class, Originally I set this to ArrayList but the warnings said needed to switch to Optional:

  public class TasksToDo {



    public static ArrayList<Task> taskList;



    public TasksToDo(){

        taskList = new ArrayList<Task>();

        taskList.add(new Task(0,"Whitepaper", "Write first draft of Whitepaper",  7));

        taskList.add(new Task(1,"Create Database Structure", "Plan required fields and tables",  1));

        taskList.add(new Task(2,"Setup ODBC Connections", "Create the ODBC Connections between SVR1 to DEV-SVR",  2));



    }



    public void addTask (int taskId, String taskTitle, String taskDescription,  int taskHours){}



    public ArrayList<Task> retrieveTask(){

        return taskList;

    }



    public Optional<Integer> retrieveTotalHours(){

    return taskList.stream().map(e -> e.getTaskHours()).reduce(Integer::sum);

    }

}

You have to unwrap the optional and grab the value in it like this. Otherwise you can't assign an Optional where int is needed.

tL.retrieveTotalHours().orElse(0);

An Optional means that the value need not be there. It is basically there to force the caller to explicitly decide what to when a value does not exist. In your case, you can specifify a default value:

jProgressBar1.setValue(tL.retrieveTotalHours().orElse(0));

However, your retrieveTotalHours method probably should not return an Optional in the first place. Stream.reduce returns Optional.empty() when the stream is empty, but in your case it probably should return 0 when the list of tasks is empty. So you can do:

public int retrieveTotalHours(){

    return taskList.stream().map(e -> e.getTaskHours()).reduce(0, Integer::sum);

}

(The 0 argument is the identity, which is returned when the stream is empty.)

or even:

public int retrieveTotalHours(){

    return taskList.stream().mapToInt(e -> e.getTaskHours()).sum();

}

Well, basically, an Optional<Integer> is not assignment compatible with int.

But Integer is (after unboxing) ... so change:

jProgressBar1.setValue(tL.retrieveTotalHours());

to

jProgressBar1.setValue(tL.retrieveTotalHours().orElse(0));

Note that you must provide an integer value when you call setValue. Null or "nothing" is not acceptable.

If you are only interested in the sum of hours, you don't need the Optional and can make it simpler:

public int retrieveTotalHours()

{

  return taskList.stream().mapToInt(e -> e.getTaskHours()).sum();

}