Declare Consumer (Setter) on object not yet created

Question

I have the following code that i want to put into a method to be reused:

    List<ClText150> names = attribute.getName().getClText150();
    for (ClText150 clText : names) {
        Locale locale = Locale.forLanguageTag(clText.getCl());
        AttributeText attributeText = textsMap.get(locale);
        if (attributeText == null) {
            attributeText = createText(locale);
            textsMap.put(locale, attributeText);
        }
        attributeText.setName(clText.getValue());
    }

This i need for different lists of ClText150 (an object from a xml). Same code i need for

List<ClText150> shortNames = attribute.getShortname().getClText150();

But this time caling setShortname with the value. The same i need for other fields. Is there a way to parametrize this setter?

I created a method doing the job:

private void handle150(List<ClText150> list, Consumer<String> setter) {
    for (ClText150 clText : list) {
        Locale locale = Locale.forLanguageTag(clText.getCl());
        AttributeText attributeText = textsMap.get(locale);
        if (attributeText == null) {
            attributeText = createText(locale);
            
        }
        setter.accept(clText.getValue());
        //attributeText.setName(clText.getValue());
    }
}

The problem is how to call this method declaring the setter of the object (attributeText) that exists only in the method. This is obviously not working: handle150(names, AttributeText::setName);

If not possible what alternatives i have to just copy paste the code?

reflection? But in my opinion, don't over complicate it. If you need to call a few setters, please write helper methods instead so that other developers understands what is going on. — JCompetence, Aug 10 '21 at 13:10
yeah reflection would be too much i think (but yes it would work). what do you mean with helper methods? How they might look? — dermoritz, Aug 10 '21 at 13:12
I just meant to use your setters as they are, without over complicating it. If you need to use attributeText.setName() and attributeText.getShortName(), use them...dont try to make it complex and generic — JCompetence, Aug 10 '21 at 13:14
but the i need to copy the code, i get names, shortnames from different lists — dermoritz, Aug 10 '21 at 13:16
I might not have understood your requirements exactly, please see the answer. — JCompetence, Aug 10 '21 at 13:39
Use `BiConsumer` and then call it like `setter.accept(attributeText, clText.getValue())`. — Michał Krzywański, Aug 10 '21 at 14:12

score 2 · Answer 1 · answered Aug 10 '21 at 14:39

I found an answer. The setter must be declared as a BiConsumer not a consumer see Lambda expression for setter

So in my case:

private void handle150(List<ClText150> list, BiConsumer<AttributeText, String> setter) {
    for (ClText150 clText : list) {
        Locale locale = Locale.forLanguageTag(clText.getCl());
        AttributeText attributeText = textsMap.get(locale);
        if (attributeText == null) {
            attributeText = createText(locale);
            
        }
        setter.accept(attributeText, clText.getValue());
    }
}

With this i can call with static method reference:

        handle150(names, AttributeText::setName);
        handle150(descriptions, AttributeText::setDescription);
        handle150(longNames, AttributeText::setLongName);
        handle150(shortNames, AttributeText::setShortName);

why and how this works is explained here.

score 1 · Answer 2 · edited Aug 10 '21 at 13:55

This is based on my understanding. I am trying to simplify this. However if you feel this does answer your question, please tell me and I will remove it.

   enum ConsumeOptions{
        NAME, SHORTNAME
    }

    private void handleAttributeText(ConsumeOptions option, AttributeText attributeText, String value){
    
           switch (option) {
                case NAME: 
                         attributeText.setName(value);
                         break;
                case SHORTNAME:
                         attributeText.setShortName(value);
                         break;
    }

private void handle150(List<ClText150> list, ConsumeOptions option) {

    for (ClText150 clText : list) {

        if (attributeText == null) {
            attributeText = createText(locale);
            
        }
           handleAttributeText(ConsumeOptions.NAME, attributeText, "newValue");
    }
}

thanks - this might indeed work and it is straight forward. But you brought-up reflection and this works also. And in my case using reflection i can handle also "ClText2000" and all other declared in xml (same methods but different classes.) I'll wait a bit but most likely also accept your answer — dermoritz, Aug 10 '21 at 13:58
I wont persuade you otherwise. Just remember to keep it simple for future developers who will maintain your code. — JCompetence, Aug 10 '21 at 13:59

Declare Consumer (Setter) on object not yet created

2 Answers2