Array in Java

  • An array is a collection of similar data types.
  • Array is a container object that hold values of homogenous type. It is also known as static data structure because size of an array must be specified at the time of its declaration.
  •  Index of array starts from zero to size-1.
  • An array can be either primitive or reference type. It gets memory in heap area
  • An array is a collection of multiple elements which has same type of data.
  • Array stores homogeneous (same data type) data contiguously in memory, and that too under one variable name, i.e. single name is assigned to the entire array elements.
  • It stores either all integers or all floating point numbers or all characters.
  • An array is a data structure used to process multiple elements with the same data type when a number of such elements are known.
  • Arrays form an important part of almost all-programming languages.
  • It provides a powerful feature and can be used as such or can be used to form complex data structures like stacks and queues.
  • An array can be defined as an infinite collection of homogeneous(similar type) elements.
  • This means that an array can store either all integers, all floating point numbers, all characters, or any other complex data type, but all of same type.
  • Arrays are always stored in consecutive memory locations.

Features of Array

  • It is always indexed. Index begins from 0.
  • It is a collection of similar data types.
  • It occupies a contiguous memory location

Flow Diagram

Flow Diagram of Array

Array Declaration

Syntax-

datatype identifier[];
        OR
 datatype[] identifier;

Example

int[] a;
float[] a;
char[] a;
short[] a;
int[][] a;

Initialization of Array

We used new operator to initialize an array.

int a[] =new int[5];
or
int a[]={2,3,4,5,6};

Accessing Array Element

In arrays, we can access the specific element by its index within square brackets.

Example

store[1]=5;

Multidimensional Array

  • Multidimensional arrays are arrays of arrays.
  • Two dimensional arrays are also called table or matrix, two dimensional arrays have two subscripts.
  • Two dimensional array inwhich elements are stored column by column is called as column major matrix.
  • Two dimensional array in which elements are stored row by row is called as row majo rmatrix.
  • First subscript denotes number of rows and second subscript denotes the number of columns.
  • The simplest form of the Multi Dimensionl Array is the Two Dimensionl Array. A Multi Dimensionl Array is essence a list of One Dimensionl Arrays.

Array Declaration

int a[][] =new int[4][5];
or
int[][] a={{2,3,4,5,6}{7,8,9,10,1}};

Accessing Array Element

For specifying both row and column in array,index start with 0.

Syntax-

arrayname[n-1][m-1];

Example

arrayname[2][3]=5;