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Array

  • Array is a collection of similar data type of elements.
  • They are stored in continuous memory space.
  • Array is treated as Object.
  • Array is fixed size & its mandatory to define size while creating an Array.
  • [] brackets used to represent Array in Java.
  • We can access values stored in Array using their index. Array index starts from Zero.

Defining Array​

There are two ways to define an Array

Method 1

int a[] = new int[2];

a[0]=10;
a[1]=20;

Method 2

int a[] = {33,3,4,5};

Iterating over an Array​

To iterate over an Array, we can either use for loop or enhanced for loop

Using For Loop
int[] array = {1, 2, 3, 4, 5};

for(int i=0;i<array.length;i++) {
    System.out.println(array[i]);
}
Using Enhanced For Loop
int[] array = {1, 2, 3, 4, 5};

for(int a: array) {
    System.out.println(a);
}

Default values​

When we create an Array, default values are assigned to all indexes

if its an int[], every index will have value 0

if its a double[], every index will have value 0.0

if its an Object array, say Student[], every index will have value null

Array Default Values
double[] arr = new double[2];

for (int i = 0; i < arr.length; i++) {
    System.out.println(arr[i]);
}
// Output
// 0.0
// 0.0

ArrayIndexOutOfBoundsException​

If we try to access index which is outside of Array size, we will get ArrayIndexOutOfBoundsException

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

System.out.println(array[7]);

// Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 
// Index 7 out of bounds for length 5