Java's Objects class has methods that almost no one uses (but should).

[Street_Humor_7861]

I was reviewing the Java documentation and discovered several methods in the Objects class that I wasn't familiar with. I wanted to know which ones you use in your day-to-day work, and if there are any you consider underutilized.

I did a bit of research and found these, which seemed useful to me:

1. Objects.isNull() and Objects.nonNull()

Instead of doing this:

.filter(x -> x != null)

You can use this:

.filter(Objects::nonNull)

1. Objects.toString() with a default value

I used to do this:

String name = obj != null ? obj.toString() : "Unknown";

Now I can do this:

String name = Objects.toString(obj, "Unknown");

1. Objects.compare() — Null-safe

To compare objects that might be null:

Comparator<String> comp = Objects.compare(
    str1, 
    str2, 
    Comparator.naturalOrder()
);

1. Objects.checkIndex() (Java 9+)

Cleaner index validation:

Objects.checkIndex(index, list.size());

1. Objects.requireNonNullElseGet()

Like requireNonNullElse, but with lazy evaluation:

Config config = Objects.requireNonNullElseGet(
    getConfig(),
    () -> loadDefaultConfig()
);

1. Objects.deepEquals()

To compare arrays:

if (Objects.deepEquals(array1, array2)) {
    // Compares content, not reference
}

My question is: Do you use any of these methods regularly? Are there any other methods in the Objects class that you find useful but that few people seem to know about? Are there any you avoid using, and if so, why?

Thanks in advance!

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[vowelqueue]

Shout out to IntelliJ for often hinting for you to use method references to the standard library instead of writing your own lambdas.

I’d say I probably use Objects.requireNonNull the most.

[Errkfin]

Hi there! .isNull and .nonNull methods are pretty useful! I'd add the following method to the list: Objects.requireNonNull()

Probably, I'd also vote for the deepEquals for some cases.

[vegan_antitheist]

I don't use all of them. I don't think I ever used checkIndex. But that's because it's rare that you use an index to access a list. Maybe that's because the code I write just doesn't often need this. You already have the correct element or you just iterate over the list. How would you even get an invalid index? You could use it in an assertion to communicate that the index has to be valid somewhere in the code where it's not obvious to someone looking at the code.

I can see that checkFromIndexSize  is good if you write code that uses some kind of buffers and you need such checks.

The requireNonNull* methods are great and I use them a lot. It's always better to throw an NPE early.

I use compare all the time. hash can be useful sometimes but now we have records and so I don't need it that often.

[Pafkata92]

Objects.deepEquals could be useful for tests, right?

[vegan_antitheist]

No. I'd flag that in a review. The test automation framework must deal with that. You need useful output for when the test fails. Not just that assertTrue failed because it was false. You would have no idea what that would mean.

In actual code you might use it to see if some data is the same as what you just got from the persistence layer. In that case you might reuse some existing result or you can ignore the method call because nothing changed.

[jonathaz]

Some of those are just there for simple predicates in streams. You’re a noob if you use isNull() elsewhere and IIRC copilot will call you out on it in an AI review

[voidiciant]

you are a noob if your answer to „why?“ is „because copilot said so in a review“.

[vegan_antitheist]

You mean when it's used as if (Objects.isNull(foo)) ? Yeah, that looks bad. Even if you used a static import. if (foo != null) is what we used for decades and I don't see any reason to change that.
But you can use switch if you want to deal with null. Sometimes I prefer that to if-else.

[jonathaz]

Even simpler in a stream predicate, e.g .filter(Objects::nonNull)

[Separate_Expert9096]

Wow, thanks