Adding element at the middle of scala.collection.immutable.list in Java

I am using scala immutable list in Java. I want to add element at the middle of this list. Can someone h开发者_开发技巧elp me on this please? Thanks

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Let sList be a Scala List, let List be the Scala List type and 42 the element to add:

final int half = sList.size /2;
final List<Int> first = sList.take(half);
final List<Int> second = sList.drop(half);
final List<Int> result = first.$colon$colon$colon( second.$colon$colon( 42 ) );

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Vague answer to a vague question:

There are several ways to split an immutable list, e.g. using take and drop. From the parts (including your middle elements), you can assemble a new immutable List, e.g. using :::, which should be called $colon$colon$colon in Java, IIRC.

Please add some code if you need more details.

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Hmmm… you are using an immutable list. The meaning of the word "immutable" is that it can not be changed - if there is a way to add an element to the middle of such a list, it would be a bug.

Edit: actually, there are probably ways to add elements in such a list - probably manipulating the corresponding data at the JVM level would do the trick - but that would still be bad, because every other program that uses an immutable list expects that list to always stay the same.