Java's Array

Arrays in Java provide a way to group like-data in a sort-of list. Data is added or removed by its index, a number representing the position of an element. Arrays in Java (and most languages) begin with an index of 0.

public class ArrayExample
	public static void main(String[] args) {
		int[] arrayOfIntegers = new int[1];
		arrayOfIntegers[0] = 2;
		System.out.println(arrayOfIntegers[0]);
	}

In the above code, we initialize an array arrayOfIntegers and set it equal to a new integer array int[]. Within the brackets of the new statement, the size of the array is specified. Array sizes are immutable in Java, meaning you cannot increase or decrease the number of elements in an array without creating a new array entirely.

Instead of explicitly stating the size of an array with new int[], we can implicitly declare the size by passing in values immediately. The array will then have a size equal to the number of elements first placed inside of it, for the duration of its life.

// cut
int[] implicitIntegerArray = {1, 2, 3};
System.out.println(implicitIntegerArray.length()); // Returns 3

Here, we implicitly declared the size of the array as three by passing in three elements.

Indexes §

Indexes of an array are integer values representing the position of a given element within an array. In Java, elements begin at index 0, thus the index of the final element is the number of elements in the array minus one. Array elements can be accessed with the following notation:

someArray[index];

This will return a copy of the value at the given index.