I was playing with Java as I am planning to switch from C# to it for cross platform purposes. I have just noticed that it has a lot of methods that just do the same thing. And I just want to know why did they do that ?
An example, the Boolean class has two methods doing the same thing in addition to the constructor which does the same thing too.
Boolean b = new Boolean(true);
Boolean b = new Boolean("true");
Boolean b = Boolean.parseBoolean(true);
Boolean b = Boolean.parseBoolean("true");
Boolean b = Boolean.valueOf(true);
Boolean b = Boolean.valueOf("true");
And I can get the boolean value either by just calling the variable itself (b) or the method b.booleanValue(). Would anyone want to call a method getting the boolean value of a boolean although he can just call the variable itself ?
What is the point ?
new Boolean(true)
and Boolean.valueOf(true)
return Boxed primitives. Real objects that can be used in collections etc. from primitive boolean values.
Boolean.parseBoolean("true")
returns the primitive boolean value.
btw,
Boolean b = Boolean.parseBoolean(true);
Boolean b = Boolean.parseBoolean("true");
are really mistakes. you are creating a primitive boolean and then auto boxing to Boolean
.
You should use valueOf(true)
or valueOf("true")
instead.
So the real use of these methods would be
Boolean b = new Boolean(true); //really this should never be used **
Boolean b = new Boolean("true"); //really this should never be used **
boolean b = Boolean.parseBoolean(true);
boolean b = Boolean.parseBoolean("true");
Boolean b = Boolean.valueOf(true);
Boolean b = Boolean.valueOf("true");
** don't use this as you are just creating objects needlessly. Using valueOf
allows for reusing existing Boolean
objects. Since Boolean
s are immutable this is fine.
Boolean.parseBoolean(*String*)
Boolean.valueOf(*String*)
new
Boolean.valueOf(*boolean*)
These are not same need.
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