Boolean.TRUE == myBoolean vs. Boolean.TRUE.equals(myBoolean)

java object boolean equals equality

16,091

Solution 1

How about:

System.out.println(new Boolean(true) == new Boolean(true));
System.out.println(new Boolean(true) == Boolean.TRUE);

(both print false, for the same reason as any other type of objects).

Solution 2

if (Boolean.TRUE == new Boolean(true)) {
    System.out.println("==");
}

if (Boolean.TRUE.equals(myBoolean)) {
    System.out.println("equals");
}

In this case first one is false. Only second if condition is true.

It Prints:

equals

Solution 3

It would be dangerous to use == because myBoolean may not have originated from one of the constants, but have been constructed as new Boolean(boolValue), in which case == would always result in false. You can use just

myBoolean.booleanValue()

with neither == nor equals involved, giving reliable results. If you must cater for null-values as well, then there's nothing better than your equals approach.

16,091

Author by

Edd

I'm a java developer and I ain't afraid to show it

Updated on June 05, 2022

Comments

Edd almost 2 years
Is there ever a situation where using equals(Boolean) and == would return different results when dealing with Boolean objects?
```
Boolean.TRUE == myBoolean;

Boolean.TRUE.equals(myBoolean);
```
I'm not thinking about primitive types here, just Boolean objects.
Menno about 11 years

Though that would lead back to the primitive value.
Marko Topolnik about 11 years

@Aquillo You make it sound like that's a problem. Why would it be a problem? Note that the result of either of OP's expressions is the same primitive boolean.
Menno about 11 years

To me it would be a possible solution instead of a problem. Though OP stated his question is not to discuss the processing of primitives.
muneebShabbir about 11 years

why it print false? can you explain?
Marko Topolnik about 11 years

new Boolean(true) == Boolean.TRUE would showcase the issue even better.
John Dvorak about 11 years

@MarkoTopolnik primitive values are a problem with tri-state booleans (true/false/null)
muneebShabbir about 11 years

its false because we are comparing objects with == sign?
Marko Topolnik about 11 years

@Aquillo OP is only indicating that myBoolean is an object.
John Dvorak about 11 years

@MarkoTopolnik yeah... what's the shortest way to safely compare tri-state booleans?
Marko Topolnik about 11 years

@JanDvorak No, you're right: TRUE.equals(myBoolean) is the shortest way---though not to compare tri-state booleans, but to determine if one such value is true.
John Dvorak about 11 years

@MarkoTopolnik only if the left hand side is a constant or two-state boolean
Marko Topolnik about 11 years

@JanDvorak ...you mean, as in TRUE.equals(myBoolean)? :)
John Dvorak about 11 years

@MarkoTopolnik yeah, that would work. But, what if you had two tristates you wanted to check for equality?
Marko Topolnik about 11 years

@JanDvorak Then you are in for a couple more characters of code :) left == null? right == null : left.equals(right)
John Dvorak about 11 years

In ruby, neither of TrueClass, FalseClass or NilClass have a public constructor.
assylias about 11 years

@muneebShabbir The reason why it prints false is the same a for any other object: stackoverflow.com/questions/2772763/…
Edd about 11 years

Thanks for this... I wasn't sure if there are only ever 2 Boolean objects and all references point to those objects but I guess not
Ali Katkar over 2 years

Except enums. You can use == for Enum objects because Java guaranteed it is singletone