NullableJ

Java library to help dealing with 'null'.

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NullableJ

Java Uitility used to deal with ‘null’. It is designed to used with Lombok @ExtensionMethod (see here and here). This means it will be the most beneficial when used with @ExtensionMethod although you can use the utilities without that. The use of Lomlok’s extension methods particularly magnify the value of null-safty done to all the utility methods.

For example, you can write code like this…

// string CAN BE NULL.
return string._whenMatches("^[0-9]+$").map(Integer::parseInt).orElse(-1);
//            ^^^^^^^^^^^^

The above code parse the string to an int or return -1 if the string is null or does not contains an integer.

Using NullableJ

The example code above makes use of @ExtensionMethod. So for the above code to compile, the following annotation must be added to the class the above code it on using.

import nawaman.nullable.NullableJ;

...

@ExtensionMethod({ NullableJ.class })

@ExtensionMethod do have some limitations, see the “Limitations” section in my article for more information. If you do not like using @ExtensionMethod, use can straight out calling those method from NullableJ

import nawaman.nullable.NullableJ;

...

return NullableJ._whenMatches(string, "^[0-9]+$").map(Integer::parseInt).orElse(-1);

or with static import …

import static nawaman.nullable.NullableJ._as;

...

return _whenMatches(string, "^[0-9]+$").map(Integer::parseInt).orElse(-1);

See below on how to setup a Gradle or Maven to use NullableJ.

API

The best and most up-to-date way to see all the methods and how to use them is to see the unit tests. It is easy to read, promise!

In general, NullableJ is composed of two things: NullableJ and NullValues.

NullableJ

NullableJ is a utility class containing utility methods. These methods are designed to be used with Lombok’s ExtensionMethod. They can be used as normal static methods but the naming is done with the intention that they will be used with Lombok’s ExtensionMethod.

NullValues

NullValues will try to find the best candidate value to use as null calue for a given class. Find more information here.