Is there a method to find what part of array has been filled

Supposing I have an array with its length as 10.I have filled six of it.The method should return 6. Now i would like to if there is any method in API to know what part of the Array has been filled.

Now i would like to if there is any method in API to know what part of the Array has been filled.

What do you exactly want ? An array of indexes ? An array of elements ? I don't think that there is such methods in the API.

Its an array of elements

Do you have to use an array? In the Collections framework in java.util, there are a lot of classes dealing with effective element storage and retrieval.

I don't think there is such a method, I am afraid.
An array has a fixed length.

There is a potential workaround; the elements of an array are a bit like instance fields in that they have default values; booleans default to false, numbers default to 0 (or 0L 0d or 0f) and reference types default to null. You can iterate through the array counting how many elements are different from their default types. Of course if you "fill" an array with 0s that technique will give a totally misleading answer.

Alternative: create a class which incorporates an array and methods to insert and retrieve values. You can have counters for how many values have been inserted, or an array of booleans which change from false to true or vice versa whenever a value is inserted first time, and use those to count insertions.