Hello everyone! I have been running into a lot of issues understanding how to do

Question

Hello everyone! I have been running into a lot of issues understanding how to do this particular Java programming assignment. Would someone mind helping me out? The assignment is as follows:

Write a Java program to calculate the result of one of three operations (minimum, L1 norm, L2 norm) on a vector of three numbers. To begin, have the user input three numbers at the keyboard (e.g. -1 2 3). Then, ask the user to type in an operation (valid operations are “min”, “l1”, or “l2”; all letters are lowercase). Assuming the user types a valid operation, your program should compute and output to the screen the result based upon the three numbers; otherwise output an error. For “min”, the result is the minimum of the three numbers (i.e. -1). For “l1”, the result is the sum of the absolute values of the three numbers (i.e. |-1| + |2| + |3| = 1 + 2 + 3 = 6). For “l2”, the result is the square root of the sum of the squares (i.e. (1)% + (2)% + (3)% = 1 + 4 + 9 = 14 = 3.74).

Example runs:

Enter three numbers: -1 2 3

Enter operation: min

min(-1.00, 2.00, 3.00) = -1.00

Enter three numbers: -1 2 3

Enter operation: l1

l1(-1.00, 2.00, 3.00) = 6.00

Enter three numbers: -1 2 3

Enter operation: l2

l2(-1.00, 2.00, 3.00) = 3.74

Enter three numbers: -1 2 3 Enter operation: foobar

Invalid operation!

Enter three numbers: -1 2 3

Enter operation: MIN

Invalid operation!

Thank you all so much in advance! :)

Explanation / Answer

import java.text.DecimalFormat;

import java.util.Scanner;

public class MathOperations {

   public static void main(String[] args) {

       System.out.println("Enter 3 numbers");

       Scanner in = new Scanner(System.in);

       int a = in.nextInt();

       int b = in.nextInt();

       int c = in.nextInt();

       System.out.println("Enter the operation");

       String s = in.next();

       // Math.min gives min of 2 numbers

       if (s.equals("min"))

           System.out.println(Math.min(a, Math.min(b, c)));

       else if (s.equals("l1"))

           // Math.abs gives absolute value of a number

           System.out.println(Math.abs(a) + Math.abs(b) + Math.abs(c));

       else if (s.equals("l2"))

           // Double.parseDouble parses double according to format here prints

           // 2 digits after decimal

           // Math.sqrt gives squareroot of a number

           System.out.println(

                   Double.parseDouble(new DecimalFormat(".##").format(Math.sqrt((a * a) + (b * b) + (c * c)))));

       else

           System.out.println("Invalid option");

   }

}

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