Introduction:

• In Java, user input is commonly taken using the Scanner class, which is part of the java.util package.
• This class provides methods to read data of different types such as int, float, String, etc.

Program:

• Below is the program demonstrates how to take input from the user and display it:

  import java.util.Scanner; // Import Scanner class
  
  public class UserInputExample
  {
      public static void main(String[] args)
      {
          // Step 1: Create Scanner object
          Scanner scanner = new Scanner(System.in);
          
          // Step 2: Prompt the user for input
          System.out.print("Enter your name: ");
          String name = scanner.nextLine(); // Read a string input
          
          System.out.print("Enter your age: ");
          int age = scanner.nextInt(); // Read an integer input
          
          System.out.print("Enter your favorite decimal number: ");
          double favoriteNumber = scanner.nextDouble(); // Read a double input
          
          // Step 3: Display the input back to the user
          System.out.println("\nThank you for providing the details!");
          System.out.println("Name: " + name);
          System.out.println("Age: " + age);
          System.out.println("Favorite Number: " + favoriteNumber);
          
          // Step 4: Close the Scanner
          scanner.close();
      }
  }

  Output:

  Enter your name: Deepak
  Enter your age: 30
  Enter your favorite decimal number: 21.1
  
  Thank you for providing the details!
  Name: Deepak
  Age: 30
  Favorite Number: 21.1

Program Explanation:

• Scanner scanner = new Scanner(System.in);
  • Here we have created a Scanner object to read input from the standard input stream (System.in).
• Input Methods:
  • scanner.nextLine(): Here nextLine() method is used to read a line of text (String).
  • scanner.nextInt(): Here nextInt() method is used to read an integer.
  • scanner.nextDouble(): Here nextDouble() method is used to read a double-precision number.
• Closing Scanner:
  • Use scanner.close() to release the resources after input is complete.

Task:

• Create a banking application with the following options:
  1. Check Balance - Display the current balance.
  2. Deposit Money - Allow users to add money to their account (validate for non-negative amounts).
  3. Withdraw Money - Allow users to withdraw money (ensure they have sufficient balance and input is non-negative).
  4. Exit - Exit the application.
• Requirements:
  • Use conditional statements concepts i.e. if, if-else, switch, while etc for above task.
  • Validate deposit and withdrawal amounts.
    (e.g., no negative values, sufficient funds for withdrawal).
  • Allow the user to perform multiple operations until they exit.
  • Handle invalid menu choices appropriately by displaying an error message.

Solution:

• import java.util.Scanner;
  
  public class BankApp
  {
      public static void main(String[] args)
      {
          Scanner scanner = new Scanner(System.in);
          double balance = 0;
          int choice;
  
          while (true)
          {
              System.out.println("Select One Option From Below Bank App:");
              System.out.println("1. Check Balance");
              System.out.println("2. Deposit Money");
              System.out.println("3. Withdraw Money");
              System.out.println("4. Exit");
  
              System.out.print("Enter your choice: ");
              choice = scanner.nextInt();
  
              switch (choice)
              {
                  case 1:
                      System.out.println("Your current balance is: " + balance+" Rs.");
                      break;
                  case 2:
                      System.out.print("Enter amount to deposit: ");
                      double deposit = scanner.nextDouble();
                      if (deposit > 0)
                      {
                          balance = balance + deposit;
                          System.out.println("Amount deposited successfully.");
                      }
                      else
                      {
                          System.out.println("Invalid amount! Please enter a positive value.");
                      }
                      break;
                  case 3:
                      System.out.print("Enter amount to withdraw: ");
                      double withdraw = scanner.nextDouble();
                      if (withdraw > 0 && withdraw <= balance)
                      {
                          balance = balance - withdraw;
                          System.out.println("Amount withdrawn successfully.");
                      }
                      else if (withdraw <= 0)
                      {
                          System.out.println("Invalid amount! Please enter a positive value.");
                      }
                      else
                      {
                          System.out.println("Insufficient balance!");
                      }
                      break;
                  case 4:
                      System.out.println("Thank you for using our banking service.");
                      scanner.close();
                      return; // Exit the program
                  default:
                      System.out.println("Invalid choice! Please enter a number between 1 and 4.");
              }
              System.out.println("------------------------");
          }
      }
  }

  Output:

  Select One Option From Below Bank App:
  1. Check Balance
  2. Deposit Money
  3. Withdraw Money
  4. Exit
  Enter your choice: 1
  Your current balance is: 0.0 Rs.
  ------------------------
  Select One Option From Below Bank App:
  1. Check Balance
  2. Deposit Money
  3. Withdraw Money
  4. Exit
  Enter your choice: 2
  Enter amount to deposit: 1000
  Amount deposited successfully.
  ------------------------
  Select One Option From Below Bank App:
  1. Check Balance
  2. Deposit Money
  3. Withdraw Money
  4. Exit
  Enter your choice: 3
  Enter amount to withdraw: 200
  Amount withdrawn successfully.
  ------------------------
  Select One Option From Below Bank App:
  1. Check Balance
  2. Deposit Money
  3. Withdraw Money
  4. Exit
  Enter your choice: 1
  Your current balance is: 800.0 Rs.
  ------------------------
  Select One Option From Below Bank App:
  1. Check Balance
  2. Deposit Money
  3. Withdraw Money
  4. Exit
  Enter your choice: 8
  Invalid choice! Please enter a number between 1 and 4.
  ------------------------
  Select One Option From Below Bank App:
  1. Check Balance
  2. Deposit Money
  3. Withdraw Money
  4. Exit
  Enter your choice: 4
  Thank you for using our banking service.