fill is a static method of the java.util.Arrays class. That is why it is invoked that way. If it were an instanced method of the actual Array class (it's not due to the way arrays are handled in Java) then you could call it as you indicated. It’s typically faster to allocate all the memory at once and assign a new array than it is to iterate over an existing array which is partly why it was designed this way. The Array class in Java is designed to be simple and lightweight. https://www.geeksforgeeks.org/static-methods-vs-instance-methods-java/ More on reddit.com

I know that a regular Java array int[] arr = new int[5]; lives in the heap and therefore it is considered as an object. Although it is considered as an object it is different from other Java obects More on stackoverflow.com

Here I need to write a method called powArray that takes a double array a and returns a new array that contains the elements of a squared. Generalize it to take a second argument and raise the elem... More on stackoverflow.com

Think of an array kind of like the cabinets in your kitchen, all in a line. Each cabinet has a specific location in your kitchen. If you were to tell someone where to find the cups when they're over at your house, you might say "They're in the cabinet over the stove, on the left". Your cabinets are used for storage of your dishes and other kitchen items, and they can be organized a certain way to make finding what you need easier. A one dimensional array is essentially a line of "cabinets" that you can store data in, where each cabinet has its own index, or location, that you reference it by. An array can be unsorted or sorted, and many algorithms exist to sort them, with some being fast, and some requiring very little extra memory. Something like .length or .size simply returns the amount of cabinets in your kitchen, or in programming terms, the number of spaces in your array. You can also make a two dimensional array, which you can think of like a grid of cubby holes at a pre-school, or more mathematically, as a matrix. These work exactly the same as a 1D array, but each element has two indexes instead of one, like an X and Y coordinate on graph paper. An array is stored linearly in memory and its indexes usually start at zero. The following example is how to create an array and fill it with numbers using Java. int[] myArray = new int[10]; //Creates an array of size 10 to store integers for(int i = 0; i < myArray.length; i++) { myArray[i] = i; } //myArray.length = 10, i = 0, loop until i > 9 //On each iteration, myArray at index i will contain the current value of i //When this loop finishes, myArray will contain 0,1,2,3,4,5,6,7,8,9 in that order Arrays are the simplest data structure you will be dealing with, but they are incredibly useful and have a huge amount of applications. Many complex data structures use arrays in some way. For example, you can represent a graph structure as a matrix, or two dimensional array, of connected edges. You can efficiently sort data without using any extra memory using a heap structure, which at its most basic form is just an array that can be sorted in place. Once you grasp arrays, you will be able to grasp the more complex structures much more easily. If there is anything else I can help you with, please let me know. More on reddit.com