Author: admin

The program shows how to Calculate the Area of Different Geometric Figures in java using a switch statement. The program uses a scanner class to take the inputs from the user.

The switch case is mostly used when it is necessary to give options to the users. The following program gives users seven cases or options to choose from and it displays results accordingly.

If you do not know the working process of the switch case statement then click the link below.

• switch statement in java

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Java Program to Calculate the Area of Different Geometric Figures using Switch Case

 //area of different geometric figures using switch case in java

 import java.util.Scanner;

 public class AreasSwitch
 {
  public static void main(String args[])
  {
    Scanner sc = new Scanner(System.in);
    
    System.out.println("To find the areas of following press:");
    System.out.println("1 for the Area of a Circle");
    System.out.println("2 for the Area of a Square");
    System.out.println("3 for the Area of a Right Angled Triangle");
    System.out.println("4 for the Area of a Rectangle");
    System.out.println("5 for the Circumference of a Circle");
    System.out.println("6 for the Perimeter of a Square");
    System.out.println("7 for the Perimeter of a Rectangle");
    System.out.println("Enter your Choice:");
    int ch = sc.nextInt();

    switch(ch)
    {
      case 1: System.out.println("Enter radius for the circle:");
              float r = sc.nextFloat();
              float area = 3.14f*r*r;
              System.out.println("Area:"+area);
              break;

      case 2: System.out.println("Enter side for square:");
              int s = sc.nextInt();
              int ae = s*s;
              System.out.println("Area:"+ae);
              break;

      case 3: System.out.println("Enter height and base for traingle:");
              float h = sc.nextFloat();
              float bs = sc.nextFloat();
              float ar = 0.5f*h*bs;
              System.out.println("Area:"+ar);
              break;

      case 4: System.out.println("Enter length and breadth for rectangle:");
              int l = sc.nextInt();
              int b = sc.nextInt();
              int aa = l*b;
              System.out.println("Area:"+aa);
              break;

      case 5: System.out.println("Enter radius for circle:");
              float rad = sc.nextFloat();
              float cir = 3.14f*2f*rad;
              System.out.println("Circumference:"+cir);
              break;


      case 6: System.out.println("Enter side for square:");
              int side = sc.nextInt();
              int peri = 4*side;
              System.out.println("Perimeter:"+peri);
              break;
      
      case 7: System.out.println("Enter length and breadth for rectangle:");
              int lg = sc.nextInt();
              int br = sc.nextInt();
              int per = 2*(lg+br);
              System.out.println("Perimeter:"+per);
              break;             

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

Output:

To find the areas of following press:
1 for the Area of a Circle
2 for the Area of a Square
3 for the Area of a Right Angled Triangle
4 for the Area of a Rectangle
5 for the Circumference of a Circle
6 for the Perimeter of a Square
7 for the Perimeter of a Rectangle
Enter your Choice:
4
Enter length and breadth for rectangle:
5
8
Area:40

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The program shows how to Check for the Negative Number in java. This program is also a good demonstration to know the working process of the if-else statement.

If you do not understand the program, perhaps you may want to learn about the if-else statement first.

• if-else statement in java

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Java Program to Check for the Negative Number

 //check for the negative number using if-else statement in java

 public class IfElseNegNumber
 {
   public static void main(String[] args) 
   {
     int num = 5;
      
      if(num < 0)  //checking condition for true
      { 
        System.out.println("Number is negative");
      }
      else //executed if the condition is false
      { 
        System.out.println("Number is positive");
      }
        
      System.out.println("Always executed");
   }
   
 }

Output:

Number is positive
Always executed

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The program shows how to List Even Numbers within a Range in java. The program uses a scanner class to take the input of the last number(n) from the user.

Therefore it displays all the even numbers between 1 to n using for loop and if statement.

If you do not know the working process of for loop and if statement then click the link below.

• for loop in java
• if statement in java

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Java Program to List all the Even Numbers within a Range

 //list even numbers using for loop

 import java.util.Scanner;

 public class ListOfEvenNumbers
 {
  
   public static void main(String[] args) 
   {
     
     Scanner scanner = new Scanner(System.in);
     
     System.out.println("Enter the last number:");
     int num = scanner.nextInt();
 
     System.out.println("Displaying even numbers between 1 to " +num);
     
     for(int i=1; i <= num; i++)
     {
      // if the number is divisible by 2 then it is even
      if( i % 2 == 0)
      {
        System.out.print(i + " ");
      }
     }
   }
 }

Output:

Enter the last number:
50
Displaying even numbers between 1 to 50
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 

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The program shows how to Generate First n Whole Numbers in java. The program is pretty simple n is already defined in a program. Although you can use the scanner class to take the inputs from the user.

If you do not know the working process of do-while loop then click the link below.

• do-while loop in java

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Java Program to Generate First n Whole Numbers

 //generate first n whole numbers using do-while loop 

 public class DoWhileNNumbers 
 {
    public static void main(String args[]) 
    {
      int num = 0;
      int N = 10;
    
      System.out.println("First 5 whole Number ");
      do
      {
       System.out.print(num + " ");
       num++; // Incrementing 
      } while ( num <= N );
    }
 }

Output:

First 5 whole Number
0 1 2 3 4 5 6 7 8 9 10

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In this tutorial, we will write a program to count the number backward in java. The program uses a scanner class to take the input from the user and with a do-while loop, it counts backward and displays the result.

If you do not know the working process of do-while loop then click the link below.

• do-while loop in java

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Java Program to Count Backward of a Number

 //count backward of a number using do-while loop in java

 import java.util.Scanner;

 public class CountBackNumber
 {
   public static void main(String args[])
   {
     int n = 5;
     Scanner scanner = new Scanner(System.in);

     System.out.println("Enter the number from where you want to back count: ");
     n = scanner.nextInt();

     do {
       System.out.print(n + " ");
       n--;  // Decrementing N by 1 in each iteration
     } while (n >= 0);
   }
 }

Output:

Enter the number from where you want to back count:
10
10 9 8 7 6 5 4 3 2 1 0

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