Java Optional Explained: of() vs ofNullable() vs empty() with Examples

Optional is used to avoid null-related issues and represent a value that may or may not be present.

You have three common ways to create an Optional. Each behaves differently.

1. Optional.of()

Optional<String> opt1 = Optional.of("Java");

Meaning

This creates an Optional that must contain a non-null value.

Key Point

If you pass null, it will throw a NullPointerException.

Example

Optional<String> opt = Optional.of(null);  // Runtime Exception

When to use

Use this when you are completely sure the value is not null.

2. Optional.ofNullable()

Optional<String> opt2 = Optional.ofNullable(null);

Meaning

This creates an Optional that can handle null safely.

Behavior

If value is not null, Optional contains the value.
If value is null, Optional becomes empty.

Example

Optional<String> optA = Optional.ofNullable("Java"); // contains value
Optional<String> optB = Optional.ofNullable(null);   // empty Optional

When to use

Use this when the value may or may not be null. This is the most commonly used method in real-world applications.

3. Optional.empty()

Optional<String> opt3 = Optional.empty();

Meaning

This creates an empty Optional with no value.

Equivalent to

Optional<String> opt = Optional.ofNullable(null);

When to use

Use this when you explicitly want to represent no value.

Quick Comparison

Method	Accepts null	Behavior
of()	No	Throws exception if null
ofNullable()	Yes	Converts null to empty Optional
empty()	Yes	Always returns empty Optional

Interview Insight

A very common interview question is the difference between of() and ofNullable().

Best answer

of() is used when the value is guaranteed to be non-null and throws an exception otherwise, while ofNullable() safely handles null values by returning an empty Optional.

Key Takeaways

Use of() when null is not possible.
Use ofNullable() when null is possible.
Use empty() when you want to explicitly represent no value.