Comparing two joda DateTime instances

Question

I have a problem with the comparing two DateTime objects.

System.out.println(response.getCreationDate().toString()); // will return "2013-12-31T22:59:21.000+01:00", but...

assertThat(response.getCreationDate(), equalTo(new DateTime("2013-12-31T22:59:21+01:00"))); // will throw an assertation error with the following error

Expected: <2013-12-31T22:59:21.000+01:00>
 but: was <2013-12-31T22:59:21.000+01:00>

Anyone has an idea what am I missing here?

Btw, if you are wondering why the DateTime is displayed in GMT+1:00 zone, cause that's the timezone in which I want my DateTime objects to be by default.

Thanks!

Answer 1

DateTime inherits its equals method from AbstractInstant . It is implemented as such

public boolean equals(Object readableInstant) {
    // must be to fulfil ReadableInstant contract
    if (this == readableInstant) {
        return true;
    }
    if (readableInstant instanceof ReadableInstant == false) {
        return false;
    }
    ReadableInstant otherInstant = (ReadableInstant) readableInstant;
    return
        getMillis() == otherInstant.getMillis() &&
        FieldUtils.equals(getChronology(), otherInstant.getChronology());
}

Notice the last line comparing chronology. It's possible your instances' chronologies are different.

Answer 2

This code (example) :

    Chronology ch1 = GregorianChronology.getInstance();
    Chronology ch2 = ISOChronology.getInstance();

    DateTime dt = new DateTime("2013-12-31T22:59:21+01:00",ch1);
    DateTime dt2 = new DateTime("2013-12-31T22:59:21+01:00",ch2);

    System.out.println(dt);
    System.out.println(dt2);

    boolean b = dt.equals(dt2);

    System.out.println(b);

Will print :

2013-12-31T16:59:21.000-05:00
2013-12-31T16:59:21.000-05:00
false

You are probably comparing two DateTime s with same date but different Chronology .