No, the curly brace syntax can only be used upon declaration.
What you could do, alternatively, is assign the array to be a temporary array that you created before hand.
For example:

1. int[] tempArray = {5, 3, 4, 7};
2. myArray = tempArray;
   

Ok thank you! I think i will just do that then only slightly more code than my original idea!

Actually, I made a similar answer some time ago, calsign, and somebody reminded me of a syntax for this:

1. int[] firstArray;
2.  
3. void setup()
4. {
5.   size(400, 500);
6.   firstArray = new int[] { width, height };
7. }
8.  
9. void draw()
10. {
11.   println(firstArray);
12.   exit();
13. }

I used a case where the init couldn't be done at global level, precisely.

" firstArray would equal {5, 7} ?"
Yes (and the best way to know is to try...).
But beware, firstArray will only hold a reference to the content of the second array: change one, you will change the other!

1. int[] firstArray = { 3, 5 };
2. int[][] secondArray = { { 5, 7 }, { 9, 4 } };
6. println(firstArray);
7. firstArray = secondArray[0];
8. println(firstArray);
9. secondArray[0][1] = 42;
10. println(firstArray);