# One Dimensional Array Basic and Examples

### Basic Concept of Array:-

• An array is ordered sequence of finite data items of the same data type that shares a common name. the common name is the array name and each individual data item is known as an element of the array.

• The variable arr[i][j] represents the element in the ith row and jth column.

• The subscript for an array must be an integer value of any integer expression.

• For all arrays, the length is static and the final property stores the length of the array, i.e., number of element in the array.

• In the declaration of arrays, the size is specified using the new operator.

• In java, all arrays are created dynamically and not statically.

• Arrays can be declared as int[] arr; or int arr[]; The allocation of memory is done as arr = new int .

• Java allows the creation of multidimensional array of variant column length.

• An array is a group of contiguous related data items which are referred to by a common name. The individual data items are called the elements of the array. In java, if n is the size of the array, indexing begins at 0 and extends up to n-1.

• A one dimensional array is an array with a single index. An array has a variable named length in which the size of the array is stored.

• A two dimensional array is akin to a table. In a java, it is possible to create a two dimensional array in which each row has a different length. This can be achieved by specifying only the first dimension of the array during it’s creation and then specifying the second dimension separately for each row.

• There are various techniques to sort the element of an array. Two prominent techniques include the Straight Selection sort and the Bubble sort.

• In Straight Selection sort, the array is parsed to find smallest element. Once this element is found, it is interchanged with the first number. Then the remaining (n-1) element are scanned for the smallest number which is interchanged with the second number. This goes on till the entire array is arranged in ascending order.

• The fundamental idea behind bubble sort is to scan the array several times. Each time, the element at position i is interchanged with the element at position i+1 if the element at position I is greater than the element at position i+1. This goes on till the entire array is arranged in ascending order.

• The linear sequential search and the binary search algorithms can be used to determine whether a particular element is present in an array or not.

• In the Linear Sequential Search, the element to be searched i.e. the key is compared with every element in the array. If it is found , the index at which it is not found is noted.

### How to read an array and display array element (Example 1)

``````

import java.util.Scanner;
{
int a[];
{
a=new int ;
Scanner sc=new Scanner(System.in);
System.out.println("Enter the element of an arry:");
for (int i = 0; i<5; i++)
{
a[i]=sc.nextInt();
}
}
void printarray()
{
System.out.println("Array element are:");
for(int i:a)
System.out.println(i);
}
public static void main(String[] args)
{
ar.printarray();
}
}                             Output:
Enter the element of an arry:
1
4
3
2
6
Array element are:
1
4
3
2
6
``````

### How to read an array and display array element (Example 2)

``````

import java.io.IOException;
public class Demo
{
public static void main(String[] args)
{
System.out.println("enter the string for test of pelindrome");
try
{
char[] ch = name.toCharArray();
for(int i=0; i<ch.length; i++)
{
int ascii = (int)ch[i];
//System.out.println(ch[i]+" : "+ascii);
StringBuffer sb = new StringBuffer(name);
String name1 = sb.reverse().toString();
char[] ch1 = name1.toCharArray();
for(int j=0; j<ch1.length; j++)
{
int ascii1 = (int)ch1[i];
//System.out.println(ch1[i]+" : "+ascii1);
}
if(name.equals(name1))
{
System.out.println("palindrome word is: "+name);
break;
}
else
{
System.out.println("not palindrome word is : "+name);
break;
}
}
}
catch(IOException ex)
{
ex.printStackTrace();
}
}
}                             Output:
enter the string for test of pelindrome
digambar
not palindrome word is : digambar
enter the string for test of pelindrome
amarama
palindrome word is: amarama

``````

### Fibonacci series program in java programing using recursion (Example 3)

``````

import java.io.IOException;
public class Demo
{
public static void main(String[] args)
{
System.out.println("enter the string for test of pelindrome");
try
{
char[] ch = name.toCharArray();
for(int i=0; i<ch.length; i++)
{
int ascii = (int)ch[i];
//System.out.println(ch[i]+" : "+ascii);
StringBuffer sb = new StringBuffer(name);
String name1 = sb.reverse().toString();
char[] ch1 = name1.toCharArray();
for(int j=0; j<ch1.length; j++)
{
int ascii1 = (int)ch1[i];
//System.out.println(ch1[i]+" : "+ascii1);
}
if(name.equals(name1))
{
System.out.println("palindrome word is: "+name);
break;
}
else
{
System.out.println("not palindrome word is : "+name);
break;
}
}
}
catch(IOException ex)
{
ex.printStackTrace();
}
}
}                             Output:
Enter the element of an arry:
1
4
3
2
6
Array element are:
1
4
3
2
6
``````

### Factorial Program using recursion in java (Example 4)

``````

class Factorial
{
static int factorial(int n)
{
if (n == 0)
return 1;
else
return(n * factorial(n-1));
}
public static void main(String args[])
{
int i,fact=1;
int num=4;   /* It is the number to calculate factorial */
fact = factorial(num);
System.out.println("Factorial of "+num+" is: "+fact);
}
}                             Output:
Factorial of 4 is: 24
``````

### Armstrong Program in java(Example 5)

``````

import java.util.Scanner;
class ArmstrExmp
{
public static void main(String[] args)
{
int b=0,a,temp;
System.out.println("Enter the number for armstrong check");
Scanner sc=new Scanner(System.in);
int n=sc.nextInt();//It is the number to check armstrong (take int n=154,n=153)
temp=n;
while(n>0)
{
a=n%10;
n=n/10;
b=b+(a*a*a);
}
if(temp==b)
{
System.out.println("armstrong number");
}
else
{
System.out.println("Not armstrong number");
}
}
}                             Output:
Enter the number for armstrong check
153
armstrong number
Enter the number for armstrong check
154
Not armstrong number
``````

``````

class Calc
{
void sum(int p,int q)
{
System.out.println("The First Output is:"+(p+q));
}
void sum(int p,int q,int r)
{
System.out.println("The Second Output is:"+(p+q+r));
}
}
public class MtdOvrLod1
{
public static void main(String[] args)
{
Calc cc=new Calc();
cc.sum(20, 20);
cc.sum(10, 20, 30);
}
}                             Output:
The First Output is:40
The Second Output is:60
``````

``````

class Calc1
{
void sum(int p,int q)
{
System.out.println("The First Output is:"+(p+q));
}
void sum(double p,double q)
{
System.out.println("The Second Output is:"+(p+q));
}
}
public class MtdOvrLod2
{
public static void main(String[] args)
{
Calc1 cc=new Calc1();
cc.sum(20.5, 20.5);
cc.sum(10, 20);
}
}                             Output:
The Second Output is:41.0
The First Output is:30
``````

``````

class OverlCalc
{
void sum(int p,int q)
{
System.out.println("integer argument  method invoked");
}
void sum(long p,long q)
{
System.out.println("long argument method invoked");
}
public static void main(String args[])
{
OverlCalc obj=new OverlCalc();
obj.sum(20,20);   /* now int arg sum() method gets invoked */
}
}                             Output:
integer argument  method invoked
``````

``````

class OverCalc
{
void sum(int p,long q)
{
System.out.println("a method invoked");
}
void sum(long p,int q)
{
System.out.println("b method invoked");
}
public static void main(String args[])
{
OverCalc obj=new OverCalc ();
obj.sum(30,40);                //now ambiguity occurs
}
}                             Output:
Compile time error
``````

### main() method will be overloaded ?(Example 10)

``````

{
public static void main(int p)
{
System.out.println(p);
}
public static void main(String args[])
{
System.out.println("this is main() method invoked");
main(25);
}
}                             Output:
this is main method() invoked
25

``````

### Write a Java Program to define a class, define instance methods and overload them and use them for dynamic method invocation(Example 11)

``````

import java.lang.*;
class Sum
{
void display(int p,int q)
{
int r=p+q;
System.out.println("The sum of " + p + " & " + q + " is " + r);
}
void display(double p,double q)
{
double r=p+q;
System.out.println("The sum of " + p + " & " + q + " is " + r);
}
}
class SumDemo
{
public static void main(String arg[])
{
Sum obj=new Sum();
obj.display(20,30);
obj.display(20.2,30.2);
}
}                             Output:
The sum of 20 & 30 is 50
The sum of 20.2 & 30.2 is 50.4

``````

### Write a Java Program to define a class, describe its constructor, overload the Constructors and instantiate its object (Example 12)

``````

import java.lang.*;
class Person
{
String name;
int regno;
int marks1,marks2,marks3;
student()    // null constructor
{
name="Sumit";
regno=12345;
marks1=56;
marks2=47;
marks3=78;
}
Person (String n,int r,int m1,int m2,int m3)  // parameterized constructor
{
name=n;
regno=r;
marks1=m1;
marks2=m2;
marks3=m3;
}
Person (Person s)    // copy constructor
{
name=s.name;
regno=s.regno;
marks1=s.marks1;
marks2=s.marks2;
marks3=s.marks3;
}
void display()
{
System.out.println(name + "\t" +regno+ "\t" +marks1+ "\t" +marks2+ "\t" + marks3);
}
}
class PersonDemo
{
public static void main(String arg[])
{
Person s1=new Person ();
Person s2=new Person ("Amit",34266,58,96,84);
Person s3=new Person (s1);
s1.display();
s2.display();
s3.display();
}
}                             Output:
Sumit 12345 56 47 78
Amit 34266 58 96 84
Sumit 12345 56 47 78

``````

### Write a Java Program to define a class, define instance methods for setting and Retrieving values of instance variables and instantiate its object(Example 13)

``````

import java.lang.*;
class Employee
{
String name;
int id;
{
this.name=name;
this.id=id;
}
void putData()
{
System.out.println("Employee details are :");
System.out.println("Name :" +name);
System.out.println("ID :" +id);
}
}
class EmpDemo
{
public static void main(String arg[])
{
Employee e=new Employee();
e.getData("Sumit",95867,"Darbhanga");
e.putData();
}
}                             Output:
Employee details are :
Name : Sumit
ID :95867

``````

### Write a Java Program to demonstrate use of sub class(Example 14)

``````

import java.lang.*;
class Parent
{
int p;
void get_p(int p)
{
this.p=p;
}
void display_p()
{
System.out.println("This is from parent : p = " +p);
}
}
class Child extends Parent
{
int q;
void get_q(int q)
{
this.q=q;
}
void display_q()
{
System.out.println("This is from child : q = " +q);
}
}
class ChildDemo
{
public static void main(String arg[])
{
Child r=new Child();
r.get_p(20);
r.get_q(30);
r.display_p();
r.display_q();
}
}                             Output:
This is from parent : m = 20
This is from child : n = 30

``````

### Write a Java Program to demonstrate use of nested class.(Example 15)

``````

import java.lang.*;
class Outer
{
int m=10;
class Inner
{
int n=20;
void display()
{
System.out.println("m = "+m);
System.out.println("n = "+n);
}
}
}
class NestedDemo
{
public static void main(String arg[])
{
Outer outobj=new Outer();
Outer.Inner inobj=outobj.new Inner();
inobj.display();
}
}                             Output:
m = 10
n = 20

``````

### Write a Java Program to implement array of objects.(Example 16)

``````

import java.lang.*;
class Employee
{
private String name;
private double salary;
public Employee(String n, double s)
{
name = n;
salary = s;
}
public void print()
{
System.out.println(name + " " + salary);
}
}
public class EmployeeTest
{
public static void main(String[] args)
{
Employee[] staff = new Employee;
staff = new Employee("Digambar Thakur", 300);
staff = new Employee("Pawan Kumar", 500);
staff = new Employee("Ritesh Deshmukh", 400);
for (int i = 0; i < 3; i++)
staff[i].print();
}
}                             Output:
Digambar Thakur:300
Pawan Kumar:500
Ritesh Deshmukh:400

``````