How do I use Do-while Loop and Switch statement?

December 28, 2021

I want the user to re-attempt the delivery rating only when the default case is invoked. I am facing error – Cannot invoke "String.equals(Object)" because "response" is null. Please refer to the code below –

package programs;
import java.util.Scanner;

public class DoWhileInSwitch {

public static void main(String[] args) {
    Scanner s = new Scanner(System.in);
    String response = null; 
    do
    {
        response.equals(null);
        System.out.println("Enter the rating of the delivery partner");
        int rating = s.nextInt();
        
        switch(rating)
        {
        case 1:
        case 2:
            System.out.println("Poor service");
            break;
            
        case 3:
            System.out.println("Average service");
            break;
            
        case 4:
        case 5:
            System.out.println("Good service");
            break;
        
        default:
            System.out.println("Invalid rating. Would you like to retry");
            s.nextLine();
            response = s.nextLine();
        }
    
    }
    while(response.equals("Yes")||response.equals("Y"));
}

}

>Solution :

Just add a boolean to see if you want to redo input

EDIT:

String.equals returns a boolean.

Null.equals doesn’t exist.

You should remove these statements

EDIT 2 :

The user can choose to re-rate or not.

If he wants to re-rate, just set the boolean to true

Else, set it to false.

 public static void main(String[] args) {
            boolean retryInput = false;
            Scanner s = new Scanner(System.in);
            //String response = null; remove this
            do
            {
                // response.equals(null); remove this
                System.out.println("Enter the rating of the delivery partner");
                int rating = s.nextInt();
                
                switch(rating)
                {
                case 1:
                case 2:
                    System.out.println("Poor service");
                    break;
                    
                case 3:
                    System.out.println("Average service");
                    break;
                    
                case 4:
                case 5:
                    System.out.println("Good service");
                    break;
                
                default:
                    System.out.println("Invalid rating. Would you like to retry");
                    s.nextLine();
                    response = s.nextLine();
                    if(response.equals("Yes")) retryInput = true;
                }
            
            }
            while(retryInput);
        }

This should work