Java Array Tutorial

This entry is part 33 of 34 in the series Core Java Course

Java Array is a data structure type which is used to store multiple variables of the same type. Arrays can hold Primitives as well as Object.

Note*: Array will always be an Object in Heap. No matter what it store, primitives or Object.

Array Declaration (Syntax)

Array of Primitives

Array Of Object

 Note: You cannot include size of array in declaration.

Declaration only doesn’t create array object in heap.

Constructing an  Java Array

This is the step where array object will be created on heap. As once created size of the array can not be changed, hence size of the array needs to be provided at the time of constructing it. This size will be used by JVM while creating array object on Heap.

Note: Size of the array means how much element an array can contains.

One Dimensional Array

New keyword will be used to construct one/multi dimensional array.

Two Dimensional Array

These are array of arrays. So a two dimensional array is array of arrays of int. So when you say, you are creating two dimensional array of Long primitive it means it will be an array containing multiple elements which in itself an array of Multidimensional Array

Note: Only first part(First Dimension is required) needs the size and not the all.

Initializing Array

Once arrays created and space assigned to it next thing would be to add elements in it. Initialization of array is the place where we can do this(Adding Element in array).

Single Dimensional Array


Java Array Cheat-sheet

  • Arrays are always created in HEAP.
  • Arrays can contain both Primitives and Objects.
  • Size of Array can not be included in Declaration.
  • Declaration doesn’t create array object in heap.
Series Navigation<< Java Thread TutorialJava Enum (Enumerations) >>

16 Comments Java Array Tutorial

    1. dsb

      No it wont possible to create dynamic array.To overcome from this problem we have to know Collection.

    1. MODI

      @PARVEEN SAINI , Please provide full details. What you want to do ? Asking for PRINTING arrays program..!!!

  1. Debajyoti

    how to find a unique row from a 2D array where the row is not equals to other row or not reverse of any other row


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