switch statement In Java

/* switch statement In Java

The program below takes three inputs from the user: operator and 2 numbers.

It performs calculation based on numbers and operator entered. Then the result is displayed on the screen.

 The syntax of switch statement is:

switch (variable/expression) {
case value1:
   // statements
   break;
case value2:
   // statements
   break;
   .. .. ...
   .. .. ...
default:
   // statements
}

import java.util.Scanner;

class Test8 {
    public static void main(String[] args) {

    char operator;
    Double num1, num2, result;
   
    Scanner scanner = new Scanner(System.in);
    System.out.print("Enter operator (either +, -, * or /): ");
    operator = scanner.next().charAt(0);
    System.out.print("Enter number1 and number2 respectively: ");
    num1 = scanner.nextDouble();
    num2 = scanner.nextDouble();
   
    switch (operator) {
         case '+':
           result = num1 + num2;
       System.out.print(num1 + "+" + num2 + " = " + result);
           break;

         case '-':
           result = num1 - num2;
           System.out.print(num1 + "-" + num2 + " = " + result);
           break;

         case '*':
           result = num1 * num2;
           System.out.print(num1 + "*" + num2 + " = " + result);
           break;

         case '/':
           result = num1 / num2;
           System.out.print(num1 + "/" + num2 + " = " + result);
           break;

         default:
           System.out.println("Invalid operator!");
           break;
        }     
    }
}

When you run the program, the output will be:

Enter operator (either +, -, * or /): *
Enter number1 and number2 respectively: 10 2

10.0*2.0 = 20.0   
BUILD SUCCESSFUL (total time: 9 seconds)

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Write a Program in Java using Break statwement

class Test7 {

public static void main(String[] args) {



for (int i = 1; i <= 10; ++i) {

if (i == 5) {

break;

}

System.out.println(i);

}

}

}




When you run the program, the output will be:

1 

2

3

4
Explanation:- In the above program, when the value of a becomes 5, expression i == 5 inside the parenthesis of if statement is evaluated to true. Then, The break statement is executed terminates the

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A Simple Example of finally block in Java

class Test2
{
   public static void main(String args[]) {
      try{
int num=121/0;
System.out.println(num);
      }
      catch(ArithmeticException e){
         System.out.println("Number should not be divided by zero");
      }
      /* Finally block will always execute
       * even if there is no exception in try block
       */
      finally{
System.out.println("This is finally block");
      }
      System.out.println("Out of try-catch-finally");
   } 
}




Output :-


Number should not be divided by zero
This is finally block
Out of try-catch-finally

Here you can observe that the exception occurred in try block which has been handled in catch block, after that finally block got executed.

A finally block must be connected with a try block, you cannot use finally without a try block. You must place those statements in this block that must be executed always.

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Swap two numbers without using temporary variable in java

Swap two numbers without using temporary variable


public class swap1 {

    public static void main(String[] args) {

        float first = 18.0f, second = 64.5f;

        System.out.println("--Before swap--");
        System.out.println("First number = " + first);
        System.out.println("Second number = " + second);

        first = first - second;
        second = first + second;
        first = second - first;

        System.out.println("--After swap--");
        System.out.println("First number = " + first);
        System.out.println("Second number = " + second);
    }
}


When you run the program, the output will be:


--Before swap--
First number = 18.0
Second number = 64.5
--After swap--
First number = 64.5
Second number = 18.0
BUILD SUCCESSFUL (total time: 3 seconds)

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Write a Program to find factorial of a number entered by user

import java.util.Scanner;
public class Example1 {

    public static void main(String[] args) {

    //We will find the factorial of this number
        int number;
        System.out.println("Enter the number: ");
        Scanner scanner = new Scanner(System.in);
        number = scanner.nextInt();
        scanner.close();
        long fact = 1;
        int i = 1;
        while(i<=number)
        {
            fact = fact * i;
            i++;
        }
        System.out.println("Factorial of "+number+" is: "+fact);
    }
}

Output:-

Enter the number:

5

Factorial of 5 is: 120

--------------------------------------------------------------------------------------------------------------------
Example2 :-

Above program does not give correct result for calculating factorial of say 16.

 Because 16! is a large number and can't be stored in integer data type which is of 4 bytes.

To calculate factorial of say hundred we use BigInteger  class of java.math package.

import java.util.Scanner;
import java.math.BigInteger;

class Fact1
{
  public static void main(String args[])
  {
    int n, c;
    BigInteger inc = new BigInteger("1");
    BigInteger fact = new BigInteger("1");

    Scanner input = new Scanner(System.in);

    System.out.println("Input an integer");
    n = input.nextInt();

    for (c = 1; c <= n; c++) {
      fact = fact.multiply(inc);
      inc = inc.add(BigInteger.ONE);
    }

    System.out.println(n + "! = " + fact);
  }
}


Output:-

Input an integer
16
16! = 20922789888000

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import statement in java

Import statement in java

1. The import statement provides a convenient way to identify classes that you want to reference to your class.import java.util.Date;

2.You can import a single class or an entire package;

3. You can include multiple import statements.

import java.util.Date;

import java.util.Calender;

you could refer to a class using it's fully qualified namespace in your application, as in the following example.

java.util.Date date = new java.util.Date();

but that would lead to a lot of typing instead java provides the import statement to allow you to declare that you want a reference  a class  in another package.

Here's an example program that uses Scanner, with an import statement:

import java.util.Scanner;

public class ScannerTest{

  public static void main(String arg[]){

    // scanner gets its input from the console.

    Scanner scanner = new Scanner(System.in);

    String fname = "";

    // Get the user's name.

    System.out.print("Your name, adventurer? >");

    fname = scanner.next();

    System.out.println();

    // Print their name in a a message.

    System.out.println("Welcome, " + fname + " to  Java tutorial Blog!");

  }

}

We import just the class Scanner from java.util in the import statement in this program. If we'd been using multiple classes from java.util, we could have made all the classes in java.util accessible to us by using this import statement:

import java.util.*;

The * is a "regular expression operator" that will match any mixture of characters. Therefore, this import statement will import everything in java.util. If you have tried entering and running the example program above, you can alter the import statement to this one.

If we need multiple classes from different packages, we use an import statement for each package from which we need to import classes (or interfaces, or any other part of that package we need.) It's not unusual to see a sequence of import statements near the start of a program file:

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Check whether a number is even or odd using if...else statement

 Check whether a number is even or odd using if...else statement

import java.util.Scanner;

public class even1 {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter a number: ");
        int num = sc.nextInt();

        if(num % 2 == 0)
            System.out.println(num + " is even");
        else
            System.out.println(num + " is odd");
    }
}

When you run the program, the output will be:


Enter a number: 12
12 is even
BUILD SUCCESSFUL (total time: 6 seconds)

Explanation:-

n the above program, a Scanner object, sc is created to read a number from the user's keyboard. The entered number is then stored in a variable num.

Now, to check whether num is even or odd, we calculate its remainder using % operator and check if it is divisible by 2 or not.

For this, we use if...else statement in Java. If num is divisible by 2, we print num is even. Else, we print num is odd.

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Write a program in Java Program to get input from user

Java Program to get input from user
//Let's see the simple example of the Java Scanner class which reads the int, string and double value as an input:
//
import java.util.Scanner; 
class abc{ 
 public static void main(String args[]){ 
   Scanner sc=new Scanner(System.in); 
   
   System.out.println("Enter your rollno"); 
   int rollno=sc.nextInt(); 
   System.out.println("Enter your name"); 
   String name=sc.next(); 
   System.out.println("Enter your fee"); 
   double fee=sc.nextDouble(); 
   System.out.println("Rollno:"+rollno+" name:"+name+" fee:"+fee); 
   sc.close(); 
 } 
} 

Enter your rollno
10
Enter your name
John
Enter your fee
20000
Rollno:10 name:John fee:20000.0

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Write a program in java / example to swap two numbers without using third variable.

using System; 
  public class Swap1 
   { 
     public static void Main(string[] args) 
      { 
       int  a=5, b=10;           
       Console.WriteLine("Before swap a= "+a+" b= "+b);   
       a=a*b; //a=50 (5*10)     
       b=a/b; //b=5 (50/10)     
       a=a/b; //a=10 (50/5)   
       Console.Write("After swap a= "+a+" b= "+b);     
     } 
  }   

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Program to display the grade of student

This program calculates the grade of a student based on the marks entered by user in each subject.

Program prints the grade based on this logic.

If the average of marks is >= 80 then prints Grade ‘A’
If the average is <80 and >=60 then prints Grade ‘B’
If the average is <60 and >=40 then prints Grade ‘C’
else

prints Grade ‘D’

// Write a Program to display the grade of student

import java.util.Scanner;

public class Grade1

{

    public static void main(String args[])

    {

            /* This program assumes that the student has 6 subjects,

             * thats why I have created the array of size 6. You can

             * change this as per the requirement.

             */

        int marks[] = new int[6];

        int i;

        float total=0, avg;

        Scanner sc = new Scanner(System.in);

                       

       

        for(i=0; i<6; i++) {

           System.out.print("Enter Marks of Subject"+(i+1)+":");

           marks[i] = sc.nextInt();

           total = total + marks[i];

        }

        sc.close();

        //Calculating average here

        avg = total/6;

        System.out.print("The student Grade is:     ");

        if(avg>=80)

        {

            System.out.print("A");

        }

        else if(avg>=60 && avg<80)

        {

           System.out.print("B");

        }

        else if(avg>=40 && avg<60)

        {

            System.out.print("C");

        }

        else

        {

            System.out.print("D");

        }

    }

}

·         Explanation:-  Using Scanner class to read user input from the keyboard.

·         Using Scanner class to read a File on the disk.

·         Using Scanner class to read from a String.

Output:-

Enter Marks of Subject1:80

Enter Marks of Subject2:45

Enter Marks of Subject3:67

Enter Marks of Subject4:89

Enter Marks of Subject5:45

Enter Marks of Subject6:78

The student Grade is:     B

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Program to find sum of first n (entered by user) natural numbers

//Program to find sum of first n (entered by user) natural numbers

import java.util.Scanner;

public class abc {

    public static void main(String[] args) {

        int num, count, tot = 0;

        System.out.println("Enter the value of n:");

        //Scanner is used for reading user input

        Scanner scan = new Scanner(System.in);

        //nextInt() method reads integer entered by user

        num = scan.nextInt();

        //closing scanner after use

        scan.close();

        for(count = 1; count <= num; count++){

            tot = tot + count;

        }







        System.out.println("Sum of first "+num+" natural numbers is: "+tot);

    }

}



Output:-

Enter the value of n:

5

Sum of first 5 natural numbers is: 15

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About Me

To understand a programming language you must practice the programs, this way you can study the language faster. This page contains java programs on various java topics such as control statements, loops, classes & objects, functions, arrays etc. All the programs are tested and provided with the output.

 If you new to java and want to learn java before trying out these program, To learn Java programming, refer these tutorials in the given order. These tutorials are written for learners so even if you have no past knowledge in Java, you won’t face any difficulty understanding these tutorials(this page includes core Java tutorial and advanced Java tutorial).

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Write a program to find Larget element of an Array

public class Large1{



    public static void main(String[] args) {

        double[] numArray = { 23.4, -55, 50.0, 33.5, 55.5, 100, 5.7, -66.5 };

        double large = numArray[0];



        for (double num: numArray) {

            if(large < num)

                large = num;

        }



        System.out.format("Largest element = %.2f", large);

    }

}





When you run the program, the output will be:



debug:

Largest element = 100.00

In the above program, we store the first element of the array in the variable large.

Then, large is used to compare other elements in the array. If any number is greater than large, large is assigned the number.

In this way, the largest number is stored in large when it is printed.

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Write a Java program to compare two strings

Write a Java program to compare two strings

import java.util.Scanner;

class Compare1
{
   public static void main(String args[])
   {
      String str1, str2;
      Scanner in = new Scanner(System.in);

      System.out.println("Enter the first string");
      str1 = in.nextLine();

      System.out.println("Enter the second string");
      str2 = in.nextLine();

      if (str1.compareTo(str2) > 0)
         System.out.println("The first string is greater than the second.");
      else if (str1.compareTo(str2) < 0)
         System.out.println("The first string is smaller than the second.");
      else 
         System.out.println("Both the strings are equal.");
   }
}

Output:-

debug:
Enter the first string
India
Enter the second string
India
Both the strings are equal.
BUILD SUCCESSFUL (total time: 14 seconds)

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Write a program in java reverses a string entered by a user

// Write a program in java   reverses a string entered by a user

import java.util.*;

class Reverse1
{
   public static void main(String args[])
   {
      String str1, reverse = "";
      Scanner in = new Scanner(System.in);

      System.out.println("Enter a string to reverse");
      str1 = in.nextLine();

      int length = str1.length();

      for ( int i = length - 1 ; i >= 0 ; i-- )
         reverse = reverse + str1.charAt(i);

      System.out.println("Reverse of entered string is: "+reverse);
   }
}

Output:-

debug:
Enter a string to reverse
Welcome
Reverse of entered string is: emocleW
BUILD SUCCESSFUL (total time: 8 seconds)




import java.util.*;

class Reverse1
{
   public static void main(String args[])
   {
   

   StringBuffer a = new StringBuffer("Good Morning");
      System.out.println(a.reverse());
   }
}
 

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Fibonacci series in Java

Fibonacci series in Java

// Let's see the fibonacci series program in java without using recursion.

Example

class Fibo{  

public static void main(String args[])  

{    

 int n1=0,n2=1,n3,i,count=10;    

 System.out.print(n1+" "+n2);//printing 0 and 1    

    

 for(i=2;i<count;++i)//loop starts from 2 because 0 and 1 are already printed    

 {    

  n3=n1+n2;    

  System.out.print(" "+n3);    

  n1=n2;    

  n2=n3;    

 }    

  

}}  

OUTPUT:-

0 1 1 2 3 5 8 13 21 34BUILD SUCCESSFUL (total time: 0 seconds)

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Write a program to find Larget element of an Array

Write a program to find Larget element of an Array

public class Large1{

    public static void main(String[] args) {

        double[] numArray = { 23.4, -55, 50.0, 33.5, 55.5, 100, 5.7, -66.5 };

        double large = numArray[0];

        for (double num: numArray) {

            if(large < num)

                large = num;

        }

        System.out.format("Largest element = %.2f", large);

    }

}

When you run the program, the output will be:

debug:

Largest element = 100.00

In the above program, we store the first element of the array in the variable large.

Then, large is used to compare other elements in the array. If any number is greater than large, large is assigned the number.

In this way, the largest number is stored in large when it is printed.

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Logo

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Java Program to check Prime number or not prime

*Let's see the prime number program in java. In this java program,
we will take a number variable and check whether the number is prime or not.
*/
/* Prime Number Program in Java
Prime number in Java: Prime number is a number that is greater than 1 and divided by 1 or itself only. In other words, prime numbers can't be divided
by other numbers than itself or 1.


For example 2, 3, 5, 7, 11, 13, 17.... are the prime numbers.*/


import java.util.Scanner;
public class Prime1{   
 public static void main(String args[]){   
  int i,x=0,flag=0; 
   Scanner sc=new Scanner(System.in); 
   
   System.out.println("Enter your Number"); 
   int n=sc.nextInt(); 
  x=n/2;     
  if(n==0||n==1){ 
   System.out.println(n+" is not prime number");     
  }else{ 
   for(i=2;i<=x;i++){     
    if(n%i==0){     
     System.out.println(n+" is not prime number");     
     flag=1;     
     break;     
    }     
   }     
   if(flag==0)  { System.out.println(n+" is prime number"); } 
  }//end of else 
}   
} 


Output:-  Enter your Number
3
3 is prime number

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