Java: How can I get the size of Integer(object) array?

I'm talking about Integer object data type, not primitive int

Suppose this: 

Integer[] arr = new Integer[5];
    arr[0] = 2;
    arr[1] = 2;
    arr[2] = 3;

Then the array will look like this {2,2,3,null,null}

How can I get the size of the array? In this case, the size is 5

Jon Skeet
people
quotationmark

Same way as for any other array - you use the length field:

int length = arr.length; // 5

From the JLS section 10.7:

The members of an array type are all of the following:

  • The public final field length, which contains the number of components of the array. length may be positive or zero.
  • ...

If you want to count the non-null values, you'd use something like:

int count = 0;
for (Integer value : arr) {
    if (value != null) {
        count++;
    }
}

(I'm sure there's a clever way to do this in fewer lines using the streams API in Java 8, but let's keep it simple for now...)

people

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