Posted on Feb 19

calculator using scanner class

package afterfeb13; import java.util.Scanner; public class calculator { static int c = 0; public static void main(String[] args) { Scanner sc = new Scanner(System.in); System.out.println("Enter input for a:"); int a = sc.nextInt(); System.out.println("Enter input for b:"); int b = sc.nextInt(); int d = add(a, b); System.out.println("add : " + d); int f = sub(a, b); System.out.println("sub : " + f); int e = multiple(a, b); System.out.println("multi : " + e); float g = div(a, b); System.out.println("div : " + g); } private static int div(int a, int b) { c = a / b; return c; } private static int multiple(int a, int b) { c = a * b; return c; } private static int sub(int a, int b) { c = a - b; return c; } private static int add(int a, int b) { c = a + b; return c; } }

Output:

Enter input for a:
1548
Enter input for b:
576
add : 2124
sub : 972
multi : 891648
div : 2.0

Different way calculator:Scanner class as static

package afterfeb13; import java.util.Scanner; public class cal { static Scanner sc = new Scanner(System.in); public static void main(String[] args) { System.out.println("calculatore"); add(); sub(); multiple(); div(); } private static void div() { System.out.println("div Enter input for a:"); int a = sc.nextInt(); System.out.println("div Enter input for b:"); int b = sc.nextInt(); int c = a / b; System.out.println("add of a/b:" + c); } private static void multiple() { System.out.println("multiple Enter input for a:"); int a = sc.nextInt(); System.out.println("multiple Enter input for b:"); int b = sc.nextInt(); int c = a * b; System.out.println("add of a*b:" + c); } private static void sub() { System.out.println("sub Enter input for a:"); int a = sc.nextInt(); System.out.println("sub Enter input for b:"); int b = sc.nextInt(); int c = a - b; System.out.println("sub of a-b:" + c); } private static void add() { System.out.println("add Enter input for a:"); int a = sc.nextInt(); System.out.println("add Enter input for b:"); int b = sc.nextInt(); int c = a + b; System.out.println("add of a+b:" + c); } }

Output:

calculatore
add Enter input for a:
12
add Enter input for b:
23
add of a+b:35
sub Enter input for a:
23
sub Enter input for b:
4
sub of a-b:19
multiple Enter input for a:
23
multiple Enter input for b:
34
add of a*b:782
div Enter input for a:
45
div Enter input for b:
5
add of a/b:9

Reference(TBD):https://www.tpointtech.com/Scanner-class

Java Scanner Class Constructors(TBD)

Java Scanner Class Methods(TBD)

Top comments (2)

Dhanush • Feb 20 • Edited

Modern approach using Java 8 features:
lambdas, Streams, Maps, Exception Handling,...

package Programs; import java.util.*; import java.util.function.BiFunction; import java.util.stream.Stream; public class Calculator { private static final Map<Integer, BiFunction<Double, Double, Double>> operations = new LinkedHashMap<>(); static { operations.put(1, (a, b) -> a + b); operations.put(2, (a, b) -> a - b); operations.put(3, (a, b) -> a * b); operations.put(4, (a, b) -> b != 0 ? a / b : Double.NaN); } public static void main(String[] args) { Scanner scanner = new Scanner(System.in); boolean continueCalc = true; while (continueCalc) { System.out.println("\nSelect an operation:"); System.out.println("0. Exit"); operations.forEach((k, v) -> System.out.println(k + ". " + getOperationName(k))); String input = scanner.nextLine(); int choice; try { choice = Integer.parseInt(input); } catch (NumberFormatException e) { System.out.println("Invalid input! Exiting..."); break; } if (choice == 0) { System.out.println("Exiting the calculator. Goodbye!"); continueCalc = false; continue; } if (!operations.containsKey(choice)) { System.out.println("Invalid choice! Exiting..."); break; } System.out.println("Enter two numbers (space-separated): "); String[] parts = scanner.nextLine().split(" "); double[] numbers = null; try { numbers = Stream.of(parts) .mapToDouble(Double::parseDouble) .toArray(); } catch (NumberFormatException e) { System.out.println("Invalid number input! Exiting..."); break; } if (numbers.length < 2) { System.out.println("You must enter two numbers! Exiting..."); break; } double result = operations.get(choice).apply(numbers[0], numbers[1]); System.out.println("Result: " + result); } scanner.close(); } private static String getOperationName(int choice) { return switch (choice) { case 1 -> "Addition"; case 2 -> "Subtraction"; case 3 -> "Multiplication"; case 4 -> "Division"; default -> "Unknown"; }; } }

You might think this is too much for a calculator. But its preferred where future modifications, extensions, and error handling are important in production.
Output:

Neelakandan R • Feb 21

Thanks bro