Java - Get the first Thursday of the month

Question

I'm trying to get the first Thursday of the month

dates.forEach(date -> {
        System.out.println("Date: " + date);
        LocalDate dateT = date.with(firstInMonth(DayOfWeek.THURSDAY));
        System.out.println("First Thursday: " + dateT);
        if(date == dateT) {
            System.out.println("Date: " + date + " is the first thursday");
        }
        System.out.println("");
    });

dates is a hashset of LocalDate objects, 7 days for mon - sun They objects may be across two months (31st May, 1st June etc.)

The output of the prints is as expected, but the if is never triggered. I have the exact sae code running for the first Tuesday which runs fine.

It successfully picks up that the first Thursday of June is 2021-06-03, but the print in the if never triggers

Date: 2021-05-31
First Thursday: 2021-05-06

Date: 2021-06-06
First Thursday: 2021-06-03

Date: 2021-06-05
First Thursday: 2021-06-03

Date: 2021-06-04
First Thursday: 2021-06-03

Date: 2021-06-03
First Thursday: 2021-06-03

Date: 2021-06-02
First Thursday: 2021-06-03

Date: 2021-06-01
First Thursday: 2021-06-03

Does this answer your question? [Compare two objects with .equals() and == operator](https://stackoverflow.com/questions/13387742/compare-two-objects-with-equals-and-operator) — Ole V.V., May 22 '21 at 07:18
From [the documentation of `LocalDate`](https://docs.oracle.com/javase/10/docs/api/java/time/LocalDate.html): *This is a value-based class; use of identity-sensitive operations (including reference equality (`==`), identity hash code, or synchronization) on instances of `LocalDate` may have unpredictable results and should be avoided. The `equals` method should be used for comparisons.* — Ole V.V., May 22 '21 at 07:21

score 1 · Answer 1 · answered May 21 '21 at 10:40

dates.forEach(date -> {
        System.out.println("Date: " + date);
        LocalDate dateT = date.with(firstInMonth(DayOfWeek.THURSDAY));
        System.out.println("First Thursday: " + dateT);
        if(date.equals(dateT)) {
            System.out.println("Date: " + date + " is the first thursday");
        }
        System.out.println("");
    });

use equals() instead of == as you are comparing the object not two values.

Note : In Java, the == operator compares that two references are identical or not. Whereas the equals() method compares two objects.

score 0 · Answer 2 · answered May 21 '21 at 10:34

0

== tests that two variables are the exact same object. You should be using equals to test for equality between two different objects:

if (date.equals(dateT)) {

answered May 21 '21 at 10:34

Mureinik

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score 0 · Accepted Answer · answered May 21 '21 at 10:34

You are trying to compare two objects and not the values they are holding.

For LocalDates specifically you can use isEqual

dates.forEach(date -> {
        System.out.println("Date: " + date);
        LocalDate dateT = date.with(firstInMonth(DayOfWeek.THURSDAY));
        System.out.println("First Thursday: " + dateT);
        if(date.isEqual(dateT)) {
            System.out.println("Date: " + date + " is the first thursday");
        }
        System.out.println("");
    });

Java - Get the first Thursday of the month

3 Answers3