Make dynamic method arguments during the compilation in Java

Question

There is the big builder that is the heart of my project and that is used very frequently. I want to make every argument in every method dynamic (expect lambda expression as an agrument). Hovewer, I will need to create twice more methods (or even bigger amount), but my builder class is already too big and I don't want to waste my time, when I add another method to it.

I want to make something like lombok annotation to method to make methods able to receive Supplier<T> and T type argument at the same time. It should get value from the supplier, when it call some method, or get field from the object.

It should be something like

@DynamicArguments
public void randFunc(String string, Integer value) {
   // some code
}

randFunc("word", 1) // works
randFunc(() -> "123546", 3) // works
randFunc(() -> "123456", () -> 8) // works

I've tryed to research groovy and custom lombok annotations to do it, but it didn't help much.

Answer 1

I would use an arguments builder class.

public static class RandFuncArgs {
    private Supplier<String> string;

    private IntSupplier value;

    public RandFuncArgs() {
        string("");
        value(0);
    }

    public RandFuncArgs(String s,
                        int value) {
        string(s);
        value(value);
    }

    public String getString() {
        return s.get();
    }

    public int getValue() {
        return value.getAsInt();
    }

    public RandFuncArgs string(String s) {
        return string(() -> s);
    }

    public RandFuncArgs string(Supplier<String> s) {
        this.string = Objects.requireNonNull(s, "Argument cannot be null.");
        return this;
    }

    public RandFuncArgs value(int value) {
        return value(() -> value);
    }

    public RandFuncArgs value(IntSupplier value) {
        this.value = Objects.requireNonNull(value, "Argument cannot be null.");
        return this;
    }
}

Now your outer class just needs one method:

public void randFunc(RandFuncArgs args) {
    // ...
}

And others can call it as:

obj.randFunc(new RandFuncArgs().string("word").value(1));
obj.randFunc(new RandFuncArgs().string(() -> "123546").value(3));
obj.randFunc(new RandFuncArgs().string(() -> "123456").value(() -> 8));