Question

Pytania dotyczące zadania

Wielowątkowość w Java, Poziom 5, Lekcja 16

Rozwiązane

I have already fixed the issue but IDK why it failed the first time so please help if you have any idea. The condition which failed is the second: In the Car class, you need to add and implement a public boolean isSummer(Date date, Date summerStart, Date summerEnd) method. Before fix:

public boolean isSummer(Date date, Date summerStart, Date summerEnd) {
        if (date.before(summerEnd) || date.after(summerStart))
            return true;
        else
            return false;
    }

After fix:

public boolean isSummer(Date date, Date summerStart, Date summerEnd) {
        if (date.before(summerStart) || date.after(summerEnd))
            return false;
        else
            return true;
    }

Can anyone exmplain why it didn't worked during first attempt?

Komentarze (7)

Popularne
Najnowsze
Najstarsze

Musisz się zalogować, aby dodać komentarz

Guadalupe Gagnon

Poziom 37 , Tampa, United States

17 listopada 2022, 16:35

When you compare an object against another object, say 'a' and 'b', there is always1 of 3 possible results: a is greater than b a is less than b and the one people forget: a is equal to b In the first code clip shared, if 'date' is equal to summerStart or summerEnd then the boolean expression would be false as it is neither before or after as the test conditions state. In this case the wrong conclusion is reached. In the second code clip you shared it would be true only when the date is clearly before or clearly after summerStart and summerEnd

Kubańczyk92 QA Automation Engineer

17 listopada 2022, 17:44

thank you for the explanation! 🍻

Thomas

Poziom 41 , Bayreuth, Germany

17 listopada 2022, 20:23

Lupe may have overseen that you use the OR and not the logical AND operator. The way your 'before fix' code is written the condition is always true. Consider this easy example: determine numbers between 1 and 9. In your way that'll look similar to x < 10 || x > 0 no matter what value you choose, either of the both parts is always true and so the entire expression will be true. If however you opted for the logical AND operator things are easier here. x > 0 && x < 10, that term will evaluate to true only when x is in the range of 1 to 9. Exactly what you want. another hint: this is already a logical expression, you do not need an if condition. Instead you just return the result like

return x > 0 && x < 10;

or for the refactoring example

return date.after(summerStart) && date.before(summerEnd);

I hope I do not have a thinking error myself now :)

Guadalupe Gagnon

Poziom 37 , Tampa, United States

17 listopada 2022, 21:13

"I hope I do not have a thinking error myself now :)" His fix code says if the date is before summerStart OR after summerEnd it should return false, otherwise it should return true. Therefore any date that is in the summer months will return true.

Guadalupe Gagnon

Poziom 37 , Tampa, United States

17 listopada 2022, 21:16

The answer I originally left OP was actually my second comment as I had the same thoughts as you did and commented on that, but after rereading the code I deleted the original one and left that answer. I think it is because he switched the placement of the summerStart and SummerEnd variables in the two bits of code he shared.

Thomas

Poziom 41 , Bayreuth, Germany

17 listopada 2022, 21:43

yes, and Kubańczyk92 is asking why the first code isn't working. And that's cause it returns true for all dates. If I understood the question wrong I'm sorry.

Guadalupe Gagnon

Poziom 37 , Tampa, United States

17 listopada 2022, 22:21

ahh. i thought you were talking about the fixed code. nope, I certainly did not even catch that in the first code 😋. I guess I was mixed up more than I originally thought.