If you explicitly initialize an object array in Java, the inclusion is different from the new object []?

This question has been asked here, but I especially want to know the specific meaning of the author

I read thinking in Java, 3rd Edition Revision 4.0, Eckel displays this code segment in Chapter 4 initialization and Cleanup:

public class ArrayInit
{
  public static void main(String[] args)
  {
    Integer[] a =
    {
      new Integer(1),new Integer(2),new Integer(3),};

    Integer[] b = new Integer[]
    {
      new Integer(1),};
  }
}

And declare as follows:

I never realized that this was different from Eckel's description As far as I know, they are static size arrays I don't understand that the first is more restrictive than the second

What is he talking about?

Solution

I think this may be what the author refers to

Because of Java 5, we can declare functions using variable parameter lists

public static int newStyleSum(final int... numbers) {
    int sum = 0;
    for (final int number : numbers) {
        sum += number;
    }
    return sum;
}

They can be used to:

int s = newStyleSum(1,2,3,4);

This function is just grammar sugar Internally, an anonymous array is passed to the function

Before we have this grammar, the above example must be written as:

public static int oldStyleSum(final int[] numbers) {
    int sum = 0;
    for (int i = 0; i < numbers.length; ++i) {
        sum += numbers[i];
    }
    return sum;
}

And called

int s = oldStyleSum(new int[]{1,4});  // "second" form

But not as good as

int s = oldStyleSum({1,4});  // "first" form (Syntax error)

Even today it is still a grammatical error

This may be what he is talking about Java 5 was published in 2004, so it makes sense for the 2002 book

The new syntax is more flexible and more importantly backward compatible, so we can still do it

int s = newStyleSum(new int[]{1,4});

Or more importantly,

int[] numbers = {1,4};
int s = newStyleSum(numbers);

If we want to