Java Program to Check if Array is Empty

Java check if array is null – Java Program to Check if Array is Empty

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Java check if array is null: In the previous article, we have seen Java Program to Join Elements of String Array with Delimiter

In this article we are going to see how to check if array is empty using Java programming language.

Java Program to Check if Array is Empty

How to check if a spot in an array is empty java: Array is a data structure which stores a fixed size sequential collection of values of single type. Where with every array elements/values memory location is associated. Each array elements have it’s own index where array index starts from 0.

In Array set of variables referenced by a single variable name and it’s array index position. It is also called as a container object which contains elements of similar type.

Declaration of an array:

dataType[] arrayName; (or)                              //Declaring an array
dataType []arrayName; (or)
dataType arr[];

Instantiation of an Array:

arrayName = new datatype[size];                    //Allocating memory to array

Combining both Statements in One:

dataType[] arrayName = new dataType[size] //Declaring and Instantiating array

Initialization of an Array:

arrayName[index-0]= arrayElement1             //Initializing the array

...

arrayName[index-s]= arrayElementS

Combining all Statements in One:

dataType arrayName[ ]={e1,e2,e3};               //declaration, instantiation and initialization

Let’s see different ways to check if array is empty.

Method-1: Java Program to Check if Array is Empty By Checking if the Array is Null

Approach:

  1. Initialize the array.
  2. Check if an array is null, using if(array == null).
  3. Check if array.length is 0.

Program:

import java.util.Arrays;

public class Main 
{
    public static void main(String[] args) 
    {
        int[] arr1 = null;
        int[] arr2 = {};
        int[] arr3 = {1, 2, 3};
        isArrayEmpty(arr1);
        isArrayEmpty(arr2);
        isArrayEmpty(arr3);

    }

    public static void isArrayEmpty(int arr[]) 
    {
        if (arr == null || arr.length == 0) {
            System.out.println("Array " + Arrays.toString(arr)+ " is empty");
        } else {
            System.out.println("Array " + Arrays.toString(arr)+ " is not empty");
        }
    }
}

Output:

Array null is empty
Array [] is empty
Array [1, 2, 3] is not empty

Method-2: Java Program to Check if Array is Empty By Checking Array Length

Approach:

  1. Initialize the array.
  2. Check if the array length is equal to 0, then the array is empty.

Program:

public class Main 
{
    public static void main(String[] args) 
    {
        //Declaring an empty array
        int arr[] = {};
        //checking the length of array, if it is equal to 0
        //then the array is empty
        if(arr.length == 0) 
        {
            System.out.println("Empty Array");
        } 
        else 
        {
            System.out.println("Not an Empty Array");
        }
    }
}
Output:

Empty Array

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