Java 8 Object Null Check

In software development, null values can be a frequent source of bugs and errors, especially in languages like Java that use explicit references. Null values occur when an object reference does not refer to an instance of an object, but rather to a special value that represents the absence of a value. In Java 8, there are several ways to check for null values to avoid these bugs.

1. Traditional null check

The traditional approach to checking for null values in Java is to use the == operator to compare the reference to null. Here's an example:

This approach is straightforward but can be verbose and error-prone, especially when multiple null checks are required. Additionally, it is not very expressive and does not take advantage of some of the new language features introduced in Java 8.

3. Optional Class

Java 8 introduced the Optional class as a way to handle null values more effectively. Optional is a container object that may or may not contain a non-null value. Optional provides a number of methods to work with the contained value, such as map(), filter(), and orElse(). Here's an example:

This approach is more concise and expressive than the traditional null check. It also provides a more functional programming style by allowing the use of methods such as map() and filter().

3. requireNonNull()

Another way to check for null values in Java 8 is to use the Objects.requireNonNull() method. This method throws a NullPointerException if the passed reference is null. Here's an example:

This approach is even more concise than the Optional class, as it doesn't require an if statement. However, it can be less expressive than the Optional class because it does not provide any methods to work with the non-null value.

In addition to the three approaches mentioned above, there are a few other techniques that can be used to handle null values in Java 8.

4. isNull() and Objects.nonNull()

Java 8 also introduced the Objects.isNull() and Objects.nonNull() methods. These methods provide a more concise way to check for null values than the traditional null check. Here's an example:

The approach is similar to the traditional null check, but provides a more concise syntax.

5. map() and Optional.orElseThrow()

The Optional class also provides the map() method, which can be used to transform the contained value if it is not null. This can be useful for chaining multiple operations together. Additionally, the orElseThrow() method can be used to throw an exception if the contained value is null. Here's an example:

This approach uses the map() method to extract a property from the non-null object, and then uses orElseThrow() to handle the case where the object is null.

6. requireNonNullElse()

Finally, Java 9 introduced the Objects.requireNonNullElse() method. This method can be used to provide a default value if the passed reference is null. Here's an example:

This approach provides a concise way to handle null values and can be useful in situations where a default value is needed.

Java 8 provides several ways to check for null values, each with its own advantages and disadvantages. Developers should choose the approach that best fits their needs based on factors such as code readability, maintainability, and performance. By using these techniques, developers can avoid null-related bugs and improve the quality and reliability of their Java applications.

Here's an example program that demonstrates how to use the Optional class to check for null values in Java 8:

ObjectNullCheckExample.java

Output:

String is null
Optional String is null