CODEWITHSUNDEEP
javastringwhile-loopequalslogical-operators
John
John

Reputation: 47

Using "OR" operator in Java

This is the code. 

do {
    System.out.println("Enter Product Code: ");
    medicine = machine1.nextInt();

    if (medicine==1) {
        machine1.buy1();
        machine1.addproduct(); 
    } 
    if (medicine==2); {
        machine1.buy2();
        machine1.addproduct();
    } 
} while((String answer=='y') || (String answer=='Y'));

And it gives this error:

enter code    drugstore1.java:96: error: ')' expected
            }while((String answer=='y'))||((String answer=='Y'));
                                 ^    drugstore1.java:96: error: ';' expected
            }while((String answer=='y'))||((String answer=='Y'));
                                       ^  drugstore1.java:96: error: ';' expected
            }while((String answer=='y'))||((String answer=='Y'));
                                                          ^

It poof'ed after fixing other errors. I think I'm using it right.. But what is wrong?

Upvotes: 1

Views: 122

Answers (5)

Abdelhak
Abdelhak

Reputation: 8387

Try to use double quote and equalsignorecase method in all you while condition like this:

  while(answer.equalsignorecase("y"));

Before try to use nextLine() when you want to insert string "y" with creating variable:

  String answer= machine1.nextLine();

Like this:

  System.out.println("Enter Product Code: ");
    medicine = machine1.nextInt();
  System.out.println("Enter y if you want leave: ");
    String answer= machine1.nextLine();

Upvotes: 4

M Sach
M Sach

Reputation: 34424

it should be 

while("y".equalsIgnoreCase(answer)){// will avoid null pointer exception if answer is null

 if(medicine==1) 
            {
                machine1.buy1();
                machine1.addproduct(); 
            } 
        else if(medicine==2) // better for performance as both if conditions are mutually exclusive
            {
                machine1.buy2();
                machine1.addproduct();
            } 

}

Upvotes: 2

Andrew
Andrew

Reputation: 49656

I suggest you to write

while(answer.equalsIgnoreCase("y"));

intead of 

while((String answer=='y'))||((String answer=='Y'));

You cannot define new variables inside logical conditions.

1. String answer [X] -> answer [V]
2. answer=='y' [X] -> answer.equals("y") [V]
3. answer.equals("y") || answer.equals("Y") [V] -> answer.equalsIgnoreCase("y") [V]

4. if(medicine==2); [X] -> if (medicine == 2) [V]

Upvotes: 5

user2233125
user2233125

Reputation:

Here are some guidelines:

  • Do not declare objects inside while() statements. Did you mean while(answer=="y")?

  • Do not compare Strings using the == operator. Strings are compared with .equals(). The == only checks if the two operands are at the same physical memory location.

Upvotes: 2

David
David

Reputation: 219077

You're trying to declare variables inside your condition:

String answer=='y'

How would a variable declaration be usable as a comparison?

Where should answer be coming from? It doesn't exist anywhere in your code, so it's not clear at all what you're trying to accomplish there.

But once you do have an answer variable in your code which potentially contains some 'y' or 'Y' value, you can compare it like this:

while(answer.equalsIgnoreCase("y"))

Additionally, you have a bug here:

if(medicine==2);

That semi-colon is going to silently terminate the if block, and the following block of code will always execute regardless of the condition. Remove that semi-colon.

Upvotes: 2

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