How to write Java function that returns values of multiple data types?

Asked 2011-02-10T02:43:50.943

For example, I want to create a function that can return any number (negative, zero, or positive).

However, based on certain exceptions, I'd like the function to return Boolean FALSE

Is there a way to write a function that can return an int or a Boolean?

Ok, so this has received a lot of responses. I understand I'm simply approaching the problem incorrectly and I should throw some sort of Exception in the method. To get a better answer, I'm going to provide some example code. Please don't make fun :)

public class Quad {

  public static void main (String[] args) {

    double a, b, c;

    a=1; b=-7; c=12;
    System.out.println("x = " + quadratic(a, b, c, 1));   // x = 4.0
    System.out.println("x = " + quadratic(a, b, c, -1));  // x = 3.0


    // "invalid" coefficients. Let's throw an exception here. How do we handle the exception?
    a=4; b=4; c=16;
    System.out.println("x = " + quadratic(a, b, c, 1));   // x = NaN
    System.out.println("x = " + quadratic(a, b, c, -1));  // x = NaN

  }

  public static double quadratic(double a, double b, double c, int polarity) {

    double x = b*b - 4*a*c;

    // When x < 0, Math.sqrt(x) retruns NaN
    if (x < 0) {
      /*
        throw exception!
        I understand this code can be adjusted to accommodate 
        imaginary numbers, but for the sake of this example,
        let's just have this function throw an exception and
        say the coefficients are invalid
      */
    }

    return (-b + Math.sqrt(x) * polarity) / (2*a);

  }

}

java methods overloading

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2 Answers

no. the best you can do is return on instance of a class that handles all the things you might want to return.

something like

public class ReturnObj {
   public bool yesno; // yes or no
   public int val; // for int values
   public String mode; // mode describing what you returned, which the caller will need to understand.
}

obviously, you need to play with the names....

Also, this seems like a code smell. You might be able to remove the need to do something like this by qualifying what path you want outside of your function, and then call a specific function to get a boolean or a specific function to get an int, depending on the qualification.

answered 2011-02-10T02:46:21.947

No, one return reference to a customer.

You can write a response object that encapsulates a boolean and an int together and set the values according to your whim.

But if I was a user I'd think your design was confusing.

answered 2011-02-10T02:46:45.777

How to write Java function that returns values of multiple data types?

2 Answers

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