Java Menu Driven Program to Check Type of a Number

In Java we have primitive numeric data types for numbers that are short, byte, int, long, float and double. These numeric data types allow us to represent different integer and real numbers based on their range as a specific data type has its lower and upper range.

Below are the 6 primitive numeric data types 

byte: Range -128 to 127 (Size 1 byte)
short: Range -32,768 to 32,767 (Size 2 bytes)
int: Range -2,147,483,648 to 2,147,483,647 (Size 4 bytes)
long: Range -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 (8 bytes)
float: Range 6 to 7 decimal digits for Fractional Numbers (Size 4 bytes)
double: Range 15 decimal digits for Fractional Numbers (Size 8 bytes)

In this article we will see how to check the type of number by using Java programming language. We will be implementing the application using a switch case.

To show you some instances 

Instance-1

Suppose we have taken an integer type of value i.e. 222222 then it must show “number entered is a valid integer”.

Instance-2

Suppose we have taken a double type of value i.e 120.0 then it must show “number entered is a valid double”.

Instance-3

Suppose we have taken a float type of value i.e 2.1 then it must show “number entered is a valid float”.

Instance-4

Suppose we have taken a byte type of value i.e 23 then it must show “number entered is a valid byte”.

Instance-5

Suppose we have taken a short type of value i.e 32,765 then it must show “number entered is a valid short”.

Instance-6

Suppose we have taken a long type of value i.e 222222222222 then it must show “number entered is a valid long”.

Syntax

To check the type of number we will check its datatype. If the datatype matches then the result will be positive otherwise negative. To check it we have a function called hasNextData_Type.

Following is the syntax to check “integer datatype” −

hasNextInt()

Following is the syntax to check “double datatype” −

hasNextDouble()

Following is the syntax to check “float datatype” −

hasNextFloat()

Following is the syntax to check “byte datatype” −

hasNextByte()

Following is the syntax to check “short datatype” −

hasNextShort()

Following is the syntax to check “long datatype” −

hasNextLong()

Algorithm

Step-1 − Ask the user to enter their choice.

Step-2 − Display the menu.

Step-3 − Ask the user to input the data.

Step-4 − Use a switch case to go to the choice and perform the operation.

Step-5 − Print the result.

Let’s see the program to understand it clearly.

Example

import java.util.*;
public class Main{
   public static void main(String args[]){
      mainLoop: while (true) {
         Scanner sc = new Scanner( System.in );
         System.out.println("\n***Menu***");
         System.out.println("1. Check for Integer");
         System.out.println("2. Check for Double");
         System.out.println("3. Check for Float");
         System.out.println("4. Check for Byte");
         System.out.println("5. Check for Short");
         System.out.println("6. Check for Long");
         System.out.println("7. Terminate the program");
         System.out.println("Enter action number (1-7): ");
         int command = sc.nextInt();
         switch(command) {
            case 1:
            int input = 0;
            System.out.println("Enter an integer for its validation");
            if(sc.hasNextInt()) {
               input = sc.nextInt();
               System.out.println(input+" is a valid Integer");
            }
            else{
               System.out.println("It is not a valid Integer");
            }
            break;
            case 2:
            double input1 = 0;
            System.out.println("Enter a Double for its validation");
            if(sc.hasNextDouble()) {
               input1 = sc.nextDouble();
               System.out.println(input1+" is a valid Double");
            }
            else {
               System.out.println("It is not a valid Double");
            }
            break;
            case 3:
            float input2;
            System.out.println("Enter a Float for its validation");
            if(sc.hasNextFloat()) {
               input2 = sc.nextFloat();
               System.out.println(input2+" is a valid Float");
            }
            else{
               System.out.println("It is not a valid Float");
            }
            break;
            case 4:
            byte input3 = 0;
            System.out.println("Enter a Byte for its validation");
            if(sc.hasNextByte()) {
               input3 = sc.nextByte();
               System.out.println(input3+" is a valid Byte");
            }
            else{
               System.out.println("It is not a valid Byte");
            }
            break;
            case 5:
            short input4 = 0;
            System.out.println("Enter a Short for its validation");
            if(sc.hasNextShort()) {
               input4 = sc.nextShort();
               System.out.println(input4+" is a valid Short");
            }
            else{
               System.out.println("It is not a valid Short");
            }

            break;
            case 6:
            long input5 = 0;
               System.out.println("Enter a Short for its validation");
               if(sc.hasNextLong()) {
                  input5 = sc.nextLong();
                  System.out.println(input5+" is a valid Long");
               }
               else{
                  System.out.println("It is not a valid Long");
               }
               break;
               case 7:
               System.out.println("Program terminated");
               break mainLoop;
               default:
               System.out.println("Wrong choice!!");
         }
      }
   }
}

Output

***Menu***
1. Check for Integer
2. Check for Double
3. Check for Float
4. Check for Byte
5. Check for Short
6. Check for Long
7. Terminate the program
Enter action number (1-7):
1
Enter an integer for its validation
22222
22222 is a valid Integer

***Menu***
1. Check for Integer
2. Check for Double
3. Check for Float
4. Check for Byte
5. Check for Short
6. Check for Long
7. Terminate the program
Enter action number (1-7):
2
Enter a Double for its validation
2.4
2.4 is a valid Double

***Menu***
1. Check for Integer
2. Check for Double
3. Check for Float
4. Check for Byte
5. Check for Short
6. Check for Long
7. Terminate the program
Enter action number (1-7):
3
Enter a Float for its validation
2.5
2.5 is a valid Float

***Menu***
1. Check for Integer
2. Check for Double
3. Check for Float
4. Check for Byte
5. Check for Short
6. Check for Long
7. Terminate the program
Enter action number (1-7):
4
Enter a Byte for its validation
123
123 is a valid Byte

***Menu***
1. Check for Integer
2. Check for Double
3. Check for Float
4. Check for Byte
5. Check for Short
6. Check for Long
7. Terminate the program
Enter action number (1-7):
5
Enter a Short for its validation
1234
1234 is a valid Short

***Menu***
1. Check for Integer
2. Check for Double
3. Check for Float
4. Check for Byte
5. Check for Short
6. Check for Long
7. Terminate the program
Enter action number (1-7):
6
Enter a Short for its validation
345
345 is a valid Long

***Menu***
1. Check for Integer
2. Check for Double
3. Check for Float
4. Check for Byte
5. Check for Short
6. Check for Long
7. Terminate the program
Enter action number (1-7):
7
Program terminated

In this article, we explored how to check type of a number in Java by using menu driven approache.