Question

Title say it all:

There is a slight ambiguity in the documentation as I understand it.
First the documentation speaks about insertion-ordered LinkedHashMap’s and notes that the iteration order is not affected upon inserting an item already mapped.

Then, it introduces access-ordered LinkedHashMap’s and insists on the fact that “merely a get is a structural modification”, i.e. it affects iteration order.

But, it is not clear whether the ”put()” of an existing item is a structural modification.

I expect the answer to be yes.

Answer 1

This simple piece of code should answer your question:

final Map<String, String> x = new LinkedHashMap<>(10, 0.75f, true);
x.put("a", "a");
x.put("b", "b");
System.out.println(x);
x.put("a", "a");
System.out.println(x);

prints

{a=a, b=b}
{b=b, a=a}

Interpretation: put under an existing key, even with the same value, is a structural modification.