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derhendrik
derhendrik

Reputation: 25

constant-specific class bodies of enum in separate java file

I am currently extending a discrete-event simulation and (coming from Python) have a hard time with some design patterns of Java.

Quick outline of what I am trying to accomplish: I want to test different preprocessing procedures in a self-written simulation framework. Each way of preprocessing contains up to several hundred lines of code.

I have created an enum class with:

public enum PreProcessorType implements preprocessorUsable {

    NoPreprocessing {
        @Override
        someMethod()
    },

    SomePreprocessing {
        @Override
        someMethod()
    },

    FullPreprocessing {
        @Override
        someMethod()
    }
}

Now all these multiple methods for each preprocessing-type have become very large, making the whole PreProcessorType class unreadable. Is there a neat possibility to put the content in a different java file? Or does this defeat the whole idea of the ("constant-specific") class body of the enum?

The initial reason that I created this preproprocessing as an enum is that I can easily iterate over it in the simulation framework, like that:

PreProcessorType[] preprocessortypes = {PreProcessorType.NoPreprocessing,
                                        PreProcessorType.SomePreprocessing,
                                        PreProcessorType.FullPreprocessing}

for (PreProccesorType p : preprocessortypes){
    // do the preprocessing
    p.someMethod();
    
    // run the actual simulation
    runSimulation();
}

An alternative would be: For each preprocessing approach, write a separate java file with the corresponding class and all necessary methods (implementing the needed interface).

Is there a way that I can safe this "enum" approach and simply store the constant-specific part of each type in a separate java file for readability?

Thank you in advance!

Please also let me know if there is a major misunderstanding regarding the design here.

Upvotes: 1

Views: 85

Answers (1)

nickb
nickb

Reputation: 59699

You won't be able to save the enum body into different class files. You can accomplish the same thing with separate class files for each preprocessing type:

interface PreprocessorUsable { 
    default void someMethod() {} 
}
class NoPreprocessing implements PreprocessorUsable {}
class SomePreprocessing implements PreprocessorUsable {}
class FullPreprocessing implements PreprocessorUsable {}

Then have the PreProcessorType enum just save references to the implementations.

public enum PreProcessorType {
    NoPreprocessing(new NoPreprocessing()),
    SomePreprocessing(new SomePreprocessing()),
    FullPreprocessing(new FullPreprocessing());

    final PreprocessorUsable preprocessor;

    PreProcessorType(PreprocessorUsable preprocessor) {
        this.preprocessor = preprocessor;
    }

    public PreprocessorUsable getPreprocessor() {
        return preprocessor;
    }
}

You'd use it like so:

PreProcessorType[] preprocessortypes = {PreProcessorType.NoPreprocessing,
    PreProcessorType.SomePreprocessing,
    PreProcessorType.FullPreprocessing};

for (PreProcessorType p : preprocessortypes){
    // do the preprocessing
    p.getPreprocessor().someMethod();

    // run the actual simulation
    runSimulation();
}

Or, use a class that just holds static constants of the different implementations.

class PreProcessorTypes {
    public static final PreprocessorUsable NO_PREPROCESSING = new NoPreprocessing();
    public static final PreprocessorUsable SOME_PREPROCESSING = new SomePreprocessing();
    public static final PreprocessorUsable FULL_PREPROCESSING = new FullPreprocessing();
}

Now, you'd use the instances instead of an enum:

PreprocessorUsable preprocessors = {PreProcessorTypes.NO_PREPROCESSING,
    PreProcessorTypes.SOME_PREPROCESSING,
    PreProcessorTypes.FULL_PREPROCESSING};

for (PreprocessorUsable p : preprocessors){
    // do the preprocessing
    p.someMethod();

    // run the actual simulation
    runSimulation();
}

Upvotes: 2

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