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[urban sparrow]

<@&987246399047479336> please have a look, thanks.

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TJ-Bot

In java i can create a union type using sealed interfaces. before sealed interfaces how do you model union types? i have a class where i can only have one of two fields set at a time is creating a concrete class with two fields and checking a field not b

reating a union type in Java before sealed interfaces can be achieved by using a common superclass or interface to represent the different types that the union can hold.

For example, you can create an interface with methods that both types in the union must implement, and then create two classes that implement this interface, each representing one of the possible types.

In your case, where you have a class with two fields that can only have one set at a time, you can create an interface with methods related to these fields, and then create two classes that implement this interface - one class for each field.

You can then have a field in your main class that is of the common interface type, allowing it to hold either of the two types.

This approach allows you to model union types in Java without using sealed interfaces. However, sealed interfaces provide a more structured and concise way to define union types by explicitly specifying all the possible subtypes within the file containing the sealed interface declaration.

- AI generated response

[radiant steeple]

All objects in Java are union types, the JDK resides a chunk of memory for each object and is smart enough to reallocate memory if any variable changes. That being said, another cool thing about Java is you can check for nullness inside of the constructor, because it's essentially a mandatory function.

@short token

What do you define as a union type?

[restive mica]

I guess it would be very cumbersome to model a union type before the language supported it.

is creating a concrete class with two fields and checking a field not being null an option? can i have a precondition enforce that only one of two fields can be non null

This could be quite repetitive in that class for writing methods that have to take into account which variable is set