Java Nested If statement-Or Compared to !=

Question

I wasn't sure how to give a title for this problem, but basically this is part of my blackjack program. Also, since I did not know how to title this, I wasn't sure how to look it up, which is why I am asking here. So I am saying that when the user enters either 1 or 11 for the ace value, if they enter something other than 1 or 11, it asks the user again to put in 1 or 11. In my program everything works fine except when the user enters 1, then it just asks the question again. The program should only asks again if the input is not equal to 1 or 11. Here is my code as I made sure it always gives an ace for testing purposes:

String card1="A";
int total=0;
Scanner input_var=new Scanner(System.in);
if (card1=="A"){
    System.out.println("Do you want a 1 or 11 for the Ace?: ");
    int player_ace_selection=input_var.nextInt();
    if ((1|11)!=(player_ace_selection)){
        System.out.println("Please enter a 1 or 11: ");
        int new_selection=input_var.nextInt();
        total=total + new_selection;
    }
    else {
        total=total + player_ace_selection;
    }
}
System.out.println(total);

Thanks in advance.

Hint: .nextInt() vs .nextLine -> the first doesn't read the new line \n — Yahya
– Yahya, Commented May 19, 2017 at 0:57
There is no short form OR, you are doing a bitwise or on 1 and 11 at (1|11)!=(player_ace_selection) — Elliott Frisch
– Elliott Frisch, Commented May 19, 2017 at 0:57
card1 == "A" is not the only problem here, and it's not the main one. Voting to reopen. — Sergey Kalinichenko
– Sergey Kalinichenko, Commented May 19, 2017 at 0:58
Also use .equals() instead of == for comparing Strings i.e. card1 and "A" — Sash Sinha
– Sash Sinha, Commented May 19, 2017 at 0:58
See best way to format multiple 'or' conditions in an if statement (Java) and how do I compare strings in Java? — Elliott Frisch
– Elliott Frisch, Commented May 19, 2017 at 1:12

Sergey Kalinichenko · Accepted Answer · 2017-05-19 00:59:56Z

3

The expression (1|11) uses binary OR, which produces 11:

    11 = 01001
     1 = 00001
(11|1) = 01001

Hence, the comparison is the same as 11!=player_ace_selection

You should change the code to use logical OR, i.e.

if (1!=player_ace_selection && 11!=player_ace_selection) {
    ...
}

In addition, you need to fix card1 == "A" comparison for card1.equals("A")

answered May 19, 2017 at 0:59

Sergey Kalinichenko

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Comments

Rahul Chowdhury · Accepted Answer · 2017-05-19 01:18:00Z

1

Instead of an If statement, try a while loop. A while loop ensures that your program waits for your user to pick the right answer. You also made a mistake with your logical operations. The correct way to use "OR" in this context is to compare your user input to both '1' and '11' separately using '||'.

    String card1="A";
    int total=0;
    Scanner input_var=new Scanner(System.in);
    if (card1.equals("A")){
        System.out.println("Do you want a 1 or 11 for the Ace?: ");
        int player_ace_selection=input_var.nextInt();

        while(player_ace_selection != 1 && player_ace_selection != 11){
            System.out.println("Do you want a 1 or 11 for the Ace?: ");
            player_ace_selection = input_var.nextInt();                
        }
        total += player_ace_selection;
    }

    System.out.println(total);

edited May 19, 2017 at 1:18

answered May 19, 2017 at 1:01

Rahul Chowdhury

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7 Comments

Yahya Over a year ago

You have a great error in your code, the while loop never stops!

Elliott Frisch Over a year ago

What condition would satisfy your while loop?

Bob G. Over a year ago

Your answer keeps asking the question if user gets it wrong the first time but gets it right the second time.

Rahul Chowdhury Over a year ago

Fixed it. The condition in the while loop should have been an AND instead of OR.

Bob G. Over a year ago

Thanks, this time it worked correctly. I will go back and look at why and hows.

|

Yahya · Accepted Answer · 2017-05-19 01:08:40Z

There are some problems in your code, please consider this example and compare it with yours.

String card1="A";
int total=0;
Scanner input_var=new Scanner(System.in);
if (card1.equals("A")){ // compare the content not the reference (==)
   System.out.println("Do you want a 1 or 11 for the Ace?: ");
   try{ // wrap with try-catch block
       int player_ace_selection = Integer.parseInt(input_var.nextLine()); //read the entire line and parse the input
       if ((player_ace_selection!=1)&&(player_ace_selection!=11)){
             System.out.println("Please enter a 1 or 11: ");
             try{
                int new_selection = Integer.parseInt(input_var.nextLine()); //again read the entire line and parse the input
                total=total + new_selection;
             }catch(NumberFormatException e){
                   // do something to catch the error
             }
        }
        else {
             total=total + player_ace_selection;

        }

    }catch(NumberFormatException e){
             // do something to catch the error
    }
    System.out.println(total);

}

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