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Array Creation and Access

Array Creation and Access

Learn how to create an array and access data from it, in Java.

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Let’s build an easy scenario before moving any further. Suppose a teacher has to grade 55 papers in total. As a programmer, you don’t want to make five different variables for it. Let’s get this done with arrays.

Create an array

Look at the code below.

class CreateArray
{
    public static void main(String args[]) 
    {
        int[] marks = {100, 87, 93, 76, 45};        // Creating an array
    }
}

We take marks as integers. Look at line 5. Let’s go through it:

  • int: Type of the values you want in an array
  • []: Square brackets right after the type
  • marks: Name of the array variable

Up until now, the array marks have been declared. In the other part, we add the values. Values are added within {} (curly braces). Note: we add five values, as discussed above, when building the scenario.

⚙️ Note: Arrays can store either primitive data (like int) or object reference data (like Strings or a custom class).

The new keyword

What if, we don’t want to add values at the time of creation? For this, Java has a keyword: new. Let’s modify the program above.

class CreateArray

{

    public static void main(String args[]) 

    {

        int[] marks = new int[5];   // Creating array with 'new' keyword

    }

}

The size of an array is established at the time of creation and cannot be changed.

Access elements of an array

Square brackets ([ ]) are used to access and modify an element in an array using an index. Look at the program below.

Java
class AcessArray
{
    public static void main(String args[]) 
    {
        int[] marks = {100, 87, 93, 76, 45};    // Creating an array
        System.out.println(marks[0]);           // Acessing an element
    }
}

Initially, we make an array of five elements. Look at line 6. We print marks[0].

It prints the value at 00th index (first value): 100100 ...