Question

Can someone please help me with how to write this in Java?

You will write a program to evaluate a math expression given by a user.

• Read the input from the scanner

• Expressions should match the forms below. Note that you will need spaces between the numbers and operators for your scanner methods to work best.

- “number1 operator number2”

- “operator number1”

• Declare number1 and number2 as type integer. Test using integer values.

• You must support the following binary operations:

- ^ : exponent (“ 3 ^ 2” means 3 raised to the 2nd power

- * : multiplication (“ 3 * 2” means 3 multiplied by 2)

- + : addition (“3 + 2” means 3 plus 2)

- / : division ( “3 / 2” means 3 divided by 2, * if you want a result with decimals you will need to cast one of the numbers to double)

• You must support the following unary operations:

- # : square root (“# 5” means the square root of 5)

- ~ : absolute (“~ -5” means the absolute value of -5)

• Your program should display the result of evaluating the expression in an appropriate form. For instance, a square root should be a double or float.

Hints:

• You can use nested if statements for all your logic, but you may want to consider a switch statement for your binary operations.

• When you read from the scanner, read the next string then decide what to do, is it a #? Is it a ~? …and so on. These checks may mean moving on to read the next piece of data as an integer and display the result, or moving on to do a binary operation.

Name your class program “MathExpressions”.

Sample output:

Example 1: Enter a math expression: ~ -75 The absolute value of -75 is: 75

Example 2: Enter a math expression: # 50 The square root of 50 is 7.07

Example 3: Enter a math expression: 3 * 4 The product of 3 and 4 is 12

Example 4: Enter a math expression: 5 ^ 2 5 raised to the 2 power is 25

Answer 1

Code for the problem is as follows:

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import java.util.Scanner;
import java.lang.Math;
public class Main
{
   public static void main(String[] args) {
  
   while(true){ //while true
   Scanner sc = new Scanner(System.in); //Scanner object
       System.out.print("Enter a math expression: ");
       String s = sc.nextLine(); //get input
       String arr[] = s.split(" "); //inputs in array
       try{
       if(arr[0].equals("~")||arr[0].equals("#")){ //if first string in array is ~ or #
      
       //find abs value
       if(arr[0].equals("~"))
       System.out.println("The absolute value of "+arr[1]+" is "+Math.abs(Integer.parseInt(arr[1])));
       //find sqrt
       else{
       double roundOff = Math.round(Math.sqrt(Integer.parseInt(arr[1])) * 100.0) / 100.0;
       System.out.println("The square root of "+arr[1]+" is "+roundOff);
       }
       }
       else{
       int a = Integer.parseInt(arr[0]);
       int b = Integer.parseInt(arr[2]);
       //do operation based on the operation
       switch(arr[1]){
       case "+":
       System.out.println("The sum of "+a+" and "+b+" is "+(a+b));
       break;
       case "*":
       System.out.println("The product of "+a+" and "+b+" is "+(a*b));
       break;
       case "/":
       System.out.println(a+" divided by "+b+" is "+((double)a/b));
       break;
       case "^":
       System.out.println(a+" raised to the "+b+" power is "+(Math.pow(a,b)));
       break;
       default: // of other than these operators then throw a Exception
       throw new Exception();
       }
       }
       break;//break the while loop if all things are perfect
       }catch(Exception e){ //Catch the Exception
       System.out.println("You have not entered the expression properly!! Please enter again"); //wrong expression entered show the message and continue in while
       }
   }
   }
}

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Screenshot of the code:

Output: