be able to use InterpolatingDoubleTreeMap.put().put()... inline

[ori-coval]

Is your feature request related to a problem? Please describe.
for me it is a bit annoying not being able to use .put when creating a new tree map and also not being able to use .put() in a constants class.

Describe the solution you'd like
solution: return the tree when using .put() so you can do as the example below and add all of the data inline.
public static final InterpolatingDoubleTreeMap INTERPOLATION_MAP = new InterpolatingDoubleTreeMap().put(2.9, 62.0).put(2.52 , 55.0).put(2.15 , 50.0).put(3.59, 63.0).put(3.04, 56.0);

[ori-coval]

if this is decided to be done I have no prob implementing it.

[spacey-sooty]

I think so long as you don't have to allocate a new object each time this is a fine feature to add

[ori-coval]

no new allocation just return this

[SamCarlberg]

An API shape like Java's existing Map.of but accepting a variadic double array would be preferred.

InterpolatingDoubleTreeMap interpolationMap =
  InterpolatingDoubleTreeMap.of(
    2.90, 62,
    2.52, 55,
    2.25, 50,
    3.59, 63,
    3.04, 56
  );

[ori-coval]

I can see why some people would prefer a variadic double array but I can say for myself that I prefer chaining the .put() method for a clear separation between each pair.

so how about adding both?

[PeterJohnson]

I assume the put() call was modeled after the Java Map put() function, which returns the previous value, not the map itself. The current code returns void, but it might be confusing to return this when no other Map in Java does that (including TreeMap). https://docs.oracle.com/javase/8/docs/api/java/util/Map.html#put-K-V-

Is there a reason you want to chain here? You can always put code into a static {} block.

[ori-coval]

the reason is ease of use and readability.

I prefer the lower example it makes it easier and faster to add multiple values one after the other and keeps a clear separation between the added values, unlike a variadic double array.
a variadic double array would also be good enough for me but I think chaining would be easier, especially for beginners.

    static {
        shooterAngleInterpolation.put(2.9, 62.0);
        shooterAngleInterpolation.put(2.52, 55.0);
        shooterAngleInterpolation.put(2.15, 50.0);
        shooterAngleInterpolation.put(3.59, 63.0);
        shooterAngleInterpolation.put(3.04, 56.0);
    }

        shooterAngleInterpolation.put(2.9, 62.0)
        .put(2.52, 55.0)
        .put(2.15, 50.0)
        .put(3.59, 63.0)
        .put(3.04, 56.0);}

[KangarooKoala]

What if instead of put() it was named addEntry(), withEntry(), or something else which doesn't have an existing meaning/convention like put()?

[calcmogul]

We could implement this function from the standard library:
https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/util/Map.html#ofEntries(java.util.Map.Entry...)

I strongly suggest we don't deviate from stdlib conventions, because it's intended to act like a stdlib type.