What are
Arrays?
An
array is a group of same typed variables that are referenced by a common name.
Arrays can be any typed and one or more dimensions. A particular element can be
addressed by array name and index of the array enclosed in third bracket ([]).
Array can be declared with its initial values or can be defined with the size
and can input the values latter. An array index start from 0 by default. Length
of single dimension array can get using a function – array. length
int
a[]={1,2,3,4};
double
a[]=new double[10];
To store similar types of data under a common variable name,
instead of declaring N number of variables for the N number of data, we use an
array. An array is a collection of similar type of variables under a common
variable. Thus we can have a collection or Array of integers, floats,
characters etc., but remember that all elements of any given array must be of
the same type, i.e. we cannot have an array of numbers some of which are int
and some float etc. Either all should be int or all should be float or all
should be char. The different components of an array are called the Array
Elements. Arrays also known as subscripted variable
How to
Declare an Array:
The array having one column and multiple rows are known as single
dimensional array. Array with multiple rows and multiple columns are known as
multi-dimensional arrays.
Like all other variables, an array needs to be declared first
before it can be used. The declaration consists of stating the type of
data-type used in the array, the name of the array and the number of elements
in the array.
Single Dimensional
Array
Data
Type Array_Variable[ ] – new Data Type [Size] ;
Example
:
int
a[]=new int[20];
String
name[]=new String[20];
Suppose
we declare an array if integer with 5 elements, N[5] and when we store
first five natural numbers to it, then it will look like the following table
N[0]
|
1
|
N[1]
|
2
|
N[2]
|
3
|
N[3]
|
4
|
N[4]
|
5
|
Here N is variable and [0] to [4] is subscript
or element location. When we input data in N[0] to N[4] location we can recall
back in any point in that particular program. Above array also known as single
dimensional array. We can initialize the array with a list of
values.
Example
:
Java : int
a[]={1,5,6,7};
String
name[]={“Ashok”,”Anil”};
Initialization can be done when we use a fixed
numbers of known data but there is no shortcut method to initialize large
number of elements.
Multi-Dimensional
Array
A multi-Dimensional array declared with multiple rows and columns.
Int N[][] = new int [3][3]
Above array will look like the following table.
Example
Column[0]
|
Column[1]
|
Column[0]
|
||
Row[0]
|
Cell[0][1]
|
Cell[0][1]
|
Cell[0][2]
|
|
Row[1]
|
Cell[1][1]
|
Cell[1][1]
|
Cell[1][2]
|
|
Row[2]
|
Cell[2][1]
|
Cell[2][1]
|
Cell[2][2]
|
We can initialize the Multi-dimensional array with a list
of values too.
Int a[][]={{1,2,3},{3,4,5}};
String a[][]={{“A”,”B”},{“C”,”D”}}’;
Some example of Input and display the array elements.
Example
import
java.util.*;
import
java.util.Collections;
import
java.util.Arrays;
class Arr_Input_Output
{
public static void main(String[] args)
{
Arr_Input_Output AIR=new
Arr_Input_Output();
System.out.println("\n\tSingle Dimensional Array ");
AIR.Single();
System.out.println("\n\tSingle
Dimensional Array ");
AIR.Multi();
}
public void Single()
{
Scanner Sc=new
Scanner(System.in);
int n;
System.out.print("\n\tEnter
Size : ");
n=Sc.nextInt();
int a[]=new int[n];
System.out.println("\n\tEnter "+n+" Nos. : \n");
for(int i=0;i
{
System.out.print("\t");
a[i]=Sc.nextInt();
}
System.out.print("\n\tNos.
in Array : ");
for(int i=0;i
{
System.out.print(a[i]+"
");
}
}
public void Multi()
{
Scanner Sc=new
Scanner(System.in);
int n,m;
System.out.print("\n\tEnter
Nos. of Rows : ");
n=Sc.nextInt();
System.out.print("\n\tEnter
Nos. of Cols : ");
m=Sc.nextInt();
int a[][]=new int[n][m];
System.out.println("\n\tEnter "+(n*m)+" Nos. : \n");
for(int i=0;i
{
for(int j=0;j
{
System.out.print("\t");
a[i][j]=Sc.nextInt();
}
}
System.out.print("\n\tNos.
in Array : \n");
for(int i=0;i
{
System.out.print("\t");
for(int j=0;j
{
System.out.print(a[i][j]+"
");
}
System.out.println();
}
}
}
Output
Single Dimensional Array
Enter Size : 3
Enter 3 Nos. :
1
2
3
Nos. in Array : 1 2
3
Single Dimensional Array
Enter Nos. of Rows : 2
Enter Nos. of Cols : 2
Enter 4 Nos. :
1
2
3
4
Nos. in Array :
1
2
3
4
