JSP Interview questions and answer

1. What is JSP?

JSP stands for Java Server Pages. JSP is java server side technology to create dynamic web pages. 

JSP file compiled by JSP container and convert it into servlet file.

Check the given string is palindrome or not

Check the given string is palindrome or not:

If we reverse a string that reverse string and original string both are equal then that string is palindrome.

Example:

Original string: java

Reverse string: avaj

Both are not equal so not palindrome.

Original string: madam

Reverse string: madam

Both are equal so palindrome.

length():- length() is final method, it is applicable for String Objects. length() method returns number of characters present in the String.

chatAt() method:-

Returns the char value at the specified index. An index ranges from 0 to length()-1. The first char value of the sequence is at index 0, the next at index 1, and so on, as for array indexing.

import java.util.Scanner;

public class PalindromeTest {

    public static void main(String[] arg){

        String name,rev="";

        Scanner sc=new Scanner(System.in);

        System.out.println("Enter Name :");

        name=sc.nextLine();        

        System.out.println("length of the String : "+name.length());

        int i=name.length();//i=string length

        for(int j=i-1;j>=0;j--){

           rev=rev+name.charAt(j);

        }

        System.out.println("reverse string is : "+rev);     

    }

}

/*

Output:-

Enter Name :

java

length of the String : 4

reverse string is : avaj

*/

import java.util.Scanner;

public class PalindromeTest {

    public static void main(String[] arg){

        String name,rev="";

        Scanner sc=new Scanner(System.in);

        System.out.println("Enter Name :");

        name=sc.nextLine();        

        System.out.println("length of the String : "+name.length());

        int i=name.length();//i=string length

        for(int j=i-1;j>=0;j--){

           rev=rev+name.charAt(j);

        }

        System.out.println("reverse string is : "+rev);

        if(name.equals(rev)){

            /* check given string and reverse string are equal or not*/

          System.out.println("palindrome ");  

        }

        else{

            System.out.println("not palindrome ");  

        }

    }

}

/*

Output-1:-

Enter Name :

java

length of the String : 4

reverse string is : avaj

not palindrome 

Output-2:-

Enter Name :

madam

length of the String : 5

reverse string is : madam

palindrome

*/

find length of the string in java

To find length of the string we use length() method

length():- length() is final method, it is applicable for String Objects. Length() method returns number of characters present in the String.

import java.util.Scanner;

public class PalindromeTest {

    public static void main(String[] arg){

        Scanner sc=new Scanner(System.in);

        System.out.println("Enter Name :");

        String name=sc.nextLine();

        System.out.println("length of the String : "+name.length());  

                               /*

                               length() is final method, it is useful to find the length of the string

                               */

    }

}

/*

Enter Name :

java

length of the String : 4

*/

length vs length() in java

length:- length is final variable, it is applicable for arrays and it returns the size of an array

Example:

int[ ] a={10,20,30};

System.out.print(a.length);

Here the above array size is 3.

In this case if we give length() instead of a.length then we will get compile time error.

length():- length() is final method, it is applicable for String Objects. Length() method returns number of characters present in the String.

Example:

String s="java";

System.out.print(s.length());

Here the above String length is 4(j,a,v,a)

Example:

String[ ] s={"java","html5","css"};

System.out.println(s.length);//3

System.out.println(s.length());//error

System.out.println(s[0].length());//4

System.out.println(s[0].length);//error

In the above example

‘s’ is an array and s[0] is String

s.length and s[0].length() are true 

Note: In multi dimensional arrays length variable represents only base size but not total size of an array.

int[ ] a=new int[2][3];

System.out.println(a.length);//2

System.out.println(a[0].length);//3

If we want find total size of multi dimensional array

System.out.println(a[0].length+a[1].length);//3+3=6

Count Even numbers from 1 to n

Here in this program I showed to count the how many even numbers from 1 to n/given number.

Even numbers from 0 to 20: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20

Total even numbers from 1 to 20 :11

import java.util.Scanner;

public class EvenNumbers {

    public static void main(String[] arg){

        int number,count=0;

        Scanner sc=new Scanner(System.in);

        System.out.println("Enter any number :");

        number=sc.nextInt();

        System.out.println("Even Numbers are");

        for(int i=0;i<=number;i++){

          if(i%2==0){

              System.out.print(i+" ");

              count++;

          } 

        }

       System.out.println();

       System.out.println("total even numbers from 1 to "+number+" :"+count);

    }   

}

/*

Output:

Enter any number :

20

Even Numbers are

2 4 6 8 10 12 14 16 18 20

total even number from 1 to 20 :10

*/

Continue statement in java

Continue statement:

Continue statement is used when we want to skip the remaining code in the block then we use continue statement.

public class ContinueTest {

    public static void main(String arg[]){        

        for(int i=1;i<=10;i++){

            if(i<5){

                System.out.println("before continue : "+i);

                continue;

            }

        System.out.println("after continue : "+i);   

       }

    }

}

Armstrong number in java

A number that is equal to the sum of cube of its digits

Example:

123=(1*1*1)+(2*2*2)+(3*3*3)

123 != 36 is not equal so it is not Armstrong

371=(3*3*3)+(7*7*7)+(1*1*1)

371==371 is equal, so it is Armstrong

import java.util.Scanner;

public class Armstrong {

    public static void main(String[] arg){

        Scanner sc=new Scanner(System.in);

        System.out.println("Enter Number");

        int i=sc.nextInt();

        int j=i;

        int a,b=0;

        while(i>0){

            a=i%10;

            b=b+(a*a*a);

            i=i/10;

        }

        if(b==j){

            System.out.println(j+" is Armstrong number");

        }

        else{

            System.out.println(j+" is not Armstrong number");

        }

    }   

}

/*

Output1:

Enter Number

123

123 is not Armstrong number

Output2:

Enter Number

371

371 is Armstrong number

*/

Palindrome program in java

Check given number is palindrome or not

If we reverse a number, that reverse number and original number (given number) both are equal then that number is palindrome number.

Example:

Given number is 121

After reverse the above number, we get 121

Given number and reverse numbers are equal so 121 is palindrome

123 is not palindrome because, 123 reverse is 321 so both are not equal

 

import java.util.Scanner;

public class Palindrome {

    public static void main(String[] arg){

        Scanner sc=new Scanner(System.in);

        System.out.println("Enter a Number");

        int i=sc.nextInt();

        int j=i;

        int a,rev=0;

        while(i>0){

           a=i%10; 

           rev=rev*10+a;

           i=i/10;

        }

        System.out.println("reverse number is :"+rev); 

        if(j==rev){

            System.out.println("given number is palindrome"); 

        }

        else{

             System.out.println("given number is not palindrome");

        }        

    }    

}

/*

Output1:

Enter a Number

123

reverse number is :321

given number is not palindrome

Output2:

Enter a Number

121

reverse number is :121

given number is palindrome

*/

Print numbers in triangle format

Print numbers in triangle format

public class TriangleTest {

    public static void main(String[] arg){

        int a=1;

        for(int i=1;i<=4;i++){

            for(int space=i;space<4;space++){

            System.out.print(" ");   // for print spaces

            }

            for(int j=1;j<=i;j++){

                System.out.print(a+" ");//print number

                a++;

            }

            System.out.println();// for new line

        }

    }

/*

Output:

   1

  2 3

 4 5 6

7 8 9 10

*/

Print digit sum program in java

Print digit sum program in java

Here in this program if we enter any number, calculate and print sum

For example: number is 123

1+2+3=6, sum is 6

import java.util.Scanner;

public class DigitSum {

   public static void main(String[] arg){

        Scanner sc=new Scanner(System.in);

        System.out.println("Enter a digit : ");

        int num=sc.nextInt();

        int sum=0,a;

        System.out.print(num +" sum is ");

        while(num > 0 )  { 

          a = num % 10;

          sum = sum + a ;

          num = num / 10 ;         

      }

        System.out.println(sum);

    } 

}

/*

Output:

Enter a digit : 

1234

1234 sum is 10

*/

Print sum of digits from 1 to n program in java

Print sum of digits from 1 to n program in java

The main aim of this program is print sum of digits, for example if we want calculate sum of digit 5 we can calculate like this way 1+2+3+4+5=15

Sum of 10 digit=1+2+3+4+5+6+7+8+9+10=65

import java.util.Scanner;

public class SumOfDigit {

    public static void main(String[] arg){

        Scanner sc=new Scanner(System.in);

        System.out.println("Enter a digit :");

        int num=sc.nextInt();

        int sum=0;

        for(int i=1;i<=num;i++){

            sum+=i;//(or) sum=sum+i;

        }

        System.out.println("sum of digits from 1 to "+num +" : "+sum);

    }

}