Arrays

Arrays in Java are also objects. They need to be declared and then created. In order to declare a variable that will hold an array of integers, we use the following syntax:

int[] arr;

Notice there is no size, since we didn't create the array yet.

arr = new int[10];

This will create a new array with the size of 10. We can check the size by printing the array's length:

System.out.println(arr.length);

We can access the array and set values:

arr[0] = 4;
arr[1] = arr[0] + 5;

Java arrays are 0 based, which means the first element in an array is accessed at index 0 (e.g: arr[0], which accesses the first element). Also, as an example, an array of size 5 will only go up to index 4 due to it being 0 based.

int[] arr = new int[5];
//accesses and sets the first element
arr[0] = 4;

We can also create an array with values in the same line:

int[] arr = {1, 2, 3, 4, 5};

Don't try to print the array without a loop, it will print something nasty like [I@f7e6a96. To print out an array, use the following code:

for (int i=0; i < arr.length; i++) {
    System.out.println(arr[i]);
}

Exercise

Change the values in numbers so it will not raise an error.