Single dimensional Array in Java language

Single dimension Array in Java language

We will learn about Single dimensional Array in Java language

The array is a data type in Java. It is a collection of similar type of elements that have contiguous index based memory location. We can use one-dimensional array to store a fixed set of elements(single dimension) in Java programming language.

Always, Array index is starting from 0, not 1

Array index ending at n-1(n denotes array length)

Array length(size) starts from 1 and ends at n(n is array length)

Array declaration, creation, initiation

Declaration of single dimension Array in Java

Syntax

We can declare one dimension Array following 3 ways

method_1      -   data_type[] array_name;
method_2      -   data_type []array_name;
method_3      -   data_type array_name[];

Examples

int[] number;    //Exmple 1
int []number;  //integer array to save only integer value
int number[];

double[] zsore;  //Exmple 2
double []zsore;   //double array to save only floating point value
double zsore[];

String[] name;   //Exmple 3
String []name;    //String array to save only String value
String name[];

The data type can be a primitive data type similar int, char, double, byte etc.. or an object
An array name is an identifier

Creating a single dimension Array in Java

We can create one dimensional Array as follows

syntax

array_name=new data_type[array_length];

Example

number=new int[5];

Here, the number is an array name that can hold five number of integer values

Declaration and creation in single line

We can declare and create one dimensional Array in one line as follows

syntax

data_type []array_name=new data_type[array_length];

Example

int []number=new int[5];

Memory representation of this array

Initialization of single dimension Array in Java

We can initialize one dimensional Array as follows- index based

Method 1

Syntax

array_name[0]=element_1;       
array_name[1]=element_2;
array_name[2]=element_3;
array_name[3]=element_4;

Example

number[0]=23;  //first element of array 
number[1]=45;  //second element of array 
number[2]=76;  //third element of array 
number[3]=25;  //forth element of array

Method 2

Syntax

int[]  array_name={element_1, element_2, element_3,........., element_n }

Example

int[] marks={34,67,84,25,68,98}

typically, array length is determined by the number of values. – array length of this array is 6

At this example, we provided six values, so array length is 6, this array can hold 6 values

array length cannot be changed in the program

Memory representation of this array

Default values of the array

After the array is declared, (before to initialize) array will be filled every array index with default values in memory locations.
the default value is 0 for numeric type, null for String and false for boolean type

Example

class Array_Default{
public static void main(String args[]){
String[] names=new String[5];//array is declared, but not initilized

System.out.println(names[0]);
System.out.println(names[1]);
System.out.println(names[2]);
System.out.println(names[3]);
System.out.println(names[4]);
}

}

When the above code is executed, it produces the following results:

null
null
null
null
null

Display array elements after initialization

Program 1

class array_1dim{
public static void main (String args[]){
int x[]=new int[5]; //diclaration and creation
x[0]=35;        //initialization array element
x[1]=30;
x[2]=13;
x[3]=31;
x[4]=113;
//display every array element
System.out.println("element of array[0] is :"+x[0]);
System.out.println("element of array[1] is :"+x[1]);
System.out.println("element of array[2] is :"+x[2]);
System.out.println("element of array[3] is :"+x[3]);
System.out.println("element of array[3] is :"+x[4]);
}
}

When the above code is executed, it produces the following results:

element of array[0] is :35
element of array[1] is :30
element of array[2] is :13
element of array[3] is :31
element of array[4] is :113

Program 2

class Array_demo{
public static void main (String args[]){
int[] arr;//array declaration
arr=new int[10]; //array creation, array length - 10 integer type
arr[0]=124;//array initialization - firstt element
arr[1]=24;
arr[2]=14;
arr[3]=12;
arr[4]=104;
arr[5]=120;
arr[6]=129;
arr[7]=195;
arr[8]=145;
arr[9]=624;                            //last element

//display array elements 
System.out.println("Element of index[0] is :"+arr[0]);
System.out.println("Element of index[1] is :"+arr[1]);
System.out.println("Element of index[2] is :"+arr[2]);
System.out.println("Element of index[3] is :"+arr[3]);
System.out.println("Element of index[4] is :"+arr[4]);
System.out.println("Element of index[5] is :"+arr[5]);
System.out.println("Element of index[6] is :"+arr[6]);
System.out.println("Element of index[7] is :"+arr[7]);
System.out.println("Element of index[8] is :"+arr[8]);
System.out.println("Element of index[9] is :"+arr[9]);
}

}

When the above code is executed, it produces the following results:

element of index[0] is :124
element of index[1] is :24
element of index[2] is :14
element of index[3] is :12
element of index[4] is :104
element of index[5] is :120
element of index[6] is :129
element of index[7] is :195
element of index[8] is :145
element of index[9] is :624

Display of element of the array using for loop

we can display elements from the array using for loop as follows

for (int i=1; i<=5; i++){
System.out.print(array_name(i));
}

program 1

class arraywithfor{
public static void main(String args[]){
int[] num;          //declaration of Array 
num=new int[6];     // Creation of Array
num[0]=115;         //initiation of element for index 0
num[1]=172;         //initiation of element for index 1
num[2]=193;         //initiation of element for index 2
num[3]=607;         //initiation of element for index 3
num[4]=745;         //initiation of element for index 4
num[5]=100;         //initiation of element for index 5
System.out.println("Element of Array");
for(int i=0; i<=5; i++){
    System.out.println(num[i]);
    //Display array element using for loop
}
}

When the above code is executed, it produces the following results:

Element of Array
115
172
193
607
745
100

Display of element using for loop in Array with array length

Method 1

for(i=0; i<=array.length-1; i++) {      //i<=array.length-1
System.out.println(array_name[i]);
}

Method 2

for(i=0; i<array.length; i++) {           //i<array.length
System.out.println(array_name[i]);
}

Program 1

class array1d{
public static void main (String args[]){
int anArray[]=new int[6];
anArray[0]=345;
anArray[1]=145;
anArray[2]=365;
anArray[3]=349;
anArray[4]=355;
anArray[5]=745;

for(int i=0; i<=anArray.length-1; i++){
    System.out.println(anArray[i]);
}
    }
        }

When the above code is executed, it produces the following results:

Display of element using Enhanced for loop in Array

we can display elements from the array using enhanced for loop as follows

for int i:array_name{
System.out.print(i);
}

Program 1

class arrayforloop2{
public static void main(String args[]){
int[] num;//declaration of Array 
num=new int[6];// Creation of Array
num[0]=110;//initiation of element for index 0
num[1]=142;//initiation of element for index 1
num[2]=153;//initiation of element for index 2
num[3]=607;//initiation of element for index 3
num[4]=745;//initiation of element for index 4
num[5]=100;//initiation of element for index 5
System.out.println("Element of Array");
for(int i:num){
    System.out.println(i);
    //Display array element using for loop
}
}

When the above code is executed, it produces the following results:

Element of Array
110
142
153
607
745
100

Array and while loop in Java

we can display elements from the array using while loop as follows

while(i<=5){
System.out.print(Array_name[i]);
}

Program 1

class Array_whileloop{
    public static void main(String args[]){
        int marks[]={45,67,65,82,49,97}; // Array declaration and initiation
        int i=0;  //Start with zero for first array index
            while(i<=5){//last Array index 5
                System.out.println(marks[i]);
                i++;

        }
    }
}

When the above code is executed, it produces the following results: