CODEWITHSUNDEEP
javadesign-patterns
user3301081
user3301081

Reputation:

Java design pattern to avoid duplication

I have the following classes

public class MyCustomFactory extends SomeOther3rdPartyFactory {

    // Return our custom behaviour for the 'string' type
    @Override
    public StringType stringType() {
        return new MyCustomStringType();
    }

    // Return our custom behaviour for the 'int' type
    @Override
    public IntType intType() {
        return new MyCustomIntType();
    }

    // same for boolean, array, object etc
}

Now, for example, the custom type classes:

public class MyCustomStringType extends StringType {
    @Override
    public void enrichWithProperty(final SomePropertyObject prop) {
        super.enrichWithProperty(prop);

        if (prop.getSomeAttribute("attribute01")) {
            this.doSomething();
            this.doSomethingElse();
        }

        if (prop.getSomeAttribute("attribute02")) {
            this.doSomethingYetAgain();
        }

        // other properties and actions
    }
}

But each custom type class like the string one above might have exactly the same if (prop.getSomeAttribute("blah")) { // same thing; }

Suppose I was to add another attribute, is there a nice way I can avoid having to duplicate if statements in each custom type class that needs it? I can move each if statement to utility class but I still need to add the call to the method in the utility class. I think we can do better.

Upvotes: 1

Views: 117

Answers (1)

Jaroslaw Pawlak
Jaroslaw Pawlak

Reputation: 5588

You can create Map<String, Consumer<MyCustomStringType>>, where the key is your attribute name and value is the method call.

public class MyCustomStringType extends StringType {

    private final Map<String, Cosnumer<MyCustomStringType>> map = new HashMap<>();

    {
        map.put("attribute01", o -> {o.doSomething(); o.doSomethingElse();});
        map.put("attribute02", MyCustomStringType::doSomethingYetAgain);
        // other properties and actions
    }

    @Override
    public void enrichWithProperty(final SomePropertyObject prop) {
        super.enrichWithProperty(prop);

        map.entrySet().stream()
            .filter(entry -> prop.getSomeAttribute(entry.getKey()))
            .forEach(entry -> entry.getValue().accept(MyCustomStringType.this));
    }
}

Depending on how you initialise this class (and whether this map is always the same), you might be able to turn in into static final immutable map.

I would also recommend naming it better, but a lot here depends on your domain and what this map and loop actually do.

Upvotes: 1

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