Make a class object a certain data type in java

Question

Can I make a class object treated as another data type? I want to make an class, that can be read as a boolean object, when the object is created in a main class. For example

public class ReturnValue {
    String one = "text";
    // some code that makes this class a boolean 'true'.
    }

public class main {
    public static void main(String[] args) {
        returnValue object = new returnValue();
        if object
            System.out.println("the subclass is true.");  //so that it could print out.
    }
}

Take care about java naming convention. Class names should start with a uppercase letter — Jens, Oct 25 '17 at 12:51
are you saying you want to check if an object is a subclass of another? — Paul Harris, Oct 25 '17 at 12:51
Your `if` statement is not even valid syntax, however, notwithstanding the fact that objects of type other than `Boolean` cannot be evaluated as booleans. — John Bollinger, Oct 25 '17 at 12:53
"_// some code that makes this class a boolean 'true'._" what do you means ? — AxelH, Oct 25 '17 at 12:54
@PaulHarris I want to make an object itself into another type... — belle park, Oct 25 '17 at 12:57
@AxelH I was hoping there were some code, that would convert the subclass into a boolean value 'true' — belle park, Oct 25 '17 at 12:59

alayor · Answer 1 · 2017-10-25T12:55:36.227

3

I think the only way is creating a method that will tell you if that object is "true" according to the properties:

public class returnValue {
    String one = "text";
    // some code that makes this class a boolean 'true'.
   public boolean isTrue() {
      return "text".equals(one); // just as example.
   }
}

public class main {
    public static void main(String[] args) {
        returnValue object = new returnValue();
        if (object.isTrue())
            System.out.println("the subclass is true.");  //so that it could print out.
    }
}

edited Oct 25 '17 at 12:55

answered Oct 25 '17 at 12:54

alayor

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1

LOL! I literally ended my answer with *"...you might even call `getValue` `isTrue` or something..."* Then posted, and saw you'd used that very name above. :-) – T.J. Crowder Oct 25 '17 at 12:54

score 3 · Answer 2 · answered Oct 25 '17 at 12:54

Java doesn't have the concept of automatically converting an object to a primitive value like a boolean (other than when the object is a Boolean, of course).

In your example, Boolean would be a reasonable choice (if it has to be an object type):

public static void main(String[] args) {
    Boolean object = Boolean.TRUE;
    if (object) {
        System.out.println("the subclass is true.");  //so that it could print out.
    }
}

If you wanted to roll your own, though, you'd have to provide an accessor method for the "boolean" value of the object:

class ReturnValue {
    private boolean value;

    ReturnValue(boolean v) {
        this.value = v;
    }

    public boolean getValue() {
        return this.value;
    }
}

then

public static void main(String[] args) {
    ReturnValue object = new ReturnValue(true);
    if (object.getValue()) {
        System.out.println("the subclass is true.");  //so that it could print out.
    }
}

You might even call getValue isTrue or similar.

I was hoping Java would provide converting an object to a primitive value. Thanks a lot anyway! — belle park, Oct 25 '17 at 13:04
@bellepark: Only for the predefined classes with corresponding primitives (`Boolean` => `boolean`, `Long` => `long`, etc.), not our own classes. — T.J. Crowder, Oct 25 '17 at 13:05

Make a class object a certain data type in java

2 Answers2