在Java中调用方法之前检查参数数量

Question

In my program, I have a method which is below;

private void foo(String title, String[] subtitles, int ... subtitleValues)

My requirement is ;

• number of subtitles and subtitleValues must be equal. User can send any number of subtitles and subtitle values but as I said equal number of subtitles and subtitleValues.

I don't want to take both arguments and check their counts in foo function and say your table can not be created because of unequal subtitles and subtitleValues. What I want is; prevent user to send unequal arguments. How can I do that?

Thanks in advance

PS : I didn't find a proper title, so if you have, please feel free to change it.

Answer 1

You can't do it like this. What you can do to make your method harder to call wrongly is to use a fluent API for a builder like this:

class FooBuilder {
  public static FooBuilder withTitle(String title);
  public FooBuilder withSubtitle(String subtitle, int subtitleValue);
  public Foo build();
}

I left out the implementation for brevity. Then you can call it like this:

Foo foo = FooBuilder.withTitle("MyTitle").withSubtitle("st1", 1).withSubtitle("st2", 2).build();

Answer 2

Create a class containing a subtitle, subtitleValue pair. Have your method accept a vararg (or list, or array) of instances of this class.

Answer 3

In this case you should create probably separate class Subtitle which represents subtitles. And create appropriate constructor or method for adding subtitles one by one.

Then rephrase your foo method as:

private void foo(String title, List<Subtitle> subtitles)