How to cast Object to boolean?

Question

How can I cast a Java object into a boolean primitive

I tried like below but it doesn't work

boolean di = new Boolean(someObject).booleanValue();

The constructor Boolean(Object) is undefined

Please advise.

Dann

Answer 1

If the object is actually a Boolean instance, then just cast it:

boolean di = (Boolean) someObject;

The explicit cast will do the conversion to Boolean, and then there's the auto-unboxing to the primitive value. Or you can do that explicitly:

boolean di = ((Boolean) someObject).booleanValue();

If someObject doesn't refer to a Boolean value though, what do you want the code to do?

Neighboring

No its not a Boolean instance but has value as true or false – Dann

I'm curious about what type is the variable... :) – Domination

Assuming true / false are Strings you could use: boolean b = Boolean.parseBoolean(String.valueOf(someObject)); Be aware that this will return false for any String value other than "true" (case insensitive) and hence will return false if someObject is null. – May

@Jon Answer for the question you asked in last line, We can use instanceOf method before casting it to Boolean.This will not give the cast exception. – Clew

@vikiiii: I'm aware of instanceof, but that's a matter of how we can check it - that doesn't answer the question I asked, which is the desired behaviour. – Neighboring

@Jon If someObject doesn't refer to a Boolean value though, Lets say be a String .Ex: "true" . Then I will like to parse that String as a boolean and I will use parseBoolean method to convert the string to Boolean. Does that answers your question? If not then please answer back and let me know. – Clew

@vikiiii: Well, it answers part of it. It doesn't answer what you'd want to happen if the value actually referred to an Integer though. Or a Button. Or a FileInputStream. And of course I was asking the OP... – Neighboring

Answer 2

Assuming that yourObject.toString() returns "true" or "false", you can try

boolean b = Boolean.valueOf(yourObject.toString())

Prevost

Have trouble understanding why toString() is required. If it's not a string then it's just an object ? – Candleberry

because yourObject is an instance of type Object and the valueOf method accepts a String. – Innumerable

This should probably be Boolean.parseBoolean to avoid boxing and unboxing a Boolean. – Convergent

Answer 3

use the conditional operator "?" like this below:

int a = 1;   //in case you want to type 1 or 0 values in the constructor call 
Boolean b;   //class var.
b=(a>0?true:false);   //set it in the constructor body

Murmuration

Yes. But this is not doing what the OP asked. 1) int is not an object type, and certainly not an arbitrary object type, 2) this is not a cast. The real problem is that the original question didn't make sense, and the OP never bothered to clarify it. – Chervonets

not the real issue – Pottle