As someone who’s coming from an ancient Java world, I confess that I’ve written code like following recently:

if (obj != null && obj.getSomething() != null) {
    return obj.getSomething().getAnotherThing().equals("MyString");

Indeed it works. However, checking null repeatedly in the if-expression is not beautiful, and nested if blocks are harmful for readability. Optional.ofNullable() can help solving the issue.

I should have written the code above like following:

return Optional.ofNullable(obj)
    .filter(thing -> thing.equals("MyString"))

Optional.ofNullable() creates a wrapper object of its argument, whose type is Optional. Optional type is a type which adds nice interface for null. For example, str.length() in the following code never throws NullPointerException because the expression is inside strOpt.ifPresent():

Optional<String> strOpt = Optional.ofNullable("MyString");
strOpt.ifPresent(str -> System.out.println(str.length())); // => 8

It’s common to call map() to return a value from Optional. map() returns a value which is also of Optional type, so method chain technique is applicable with Optional. Methods like filter() are available by Optional. I don’t write about it in this article because it’s easy to guess what it means.

Let’s stop writing if (something != null) and embrace Optional.ofNullable()!