在Java中实例化布尔对象：Boolean.TRUE和Boolean.FALSE与原语

Question

I want to figure out whether

Boolean var = true;

is any better than

Boolean var = Boolean.True;

?

What is an ideological way? Which one is better comparing performance?

After all why there're instantiated Boolean objects if we have two primitives to use?

Answer 1

Your two snippets perform identically, because the Java compiler will autobox primitives to their wrapper types (which means the code is effectively identical). The primitive type boolean would typically be expected to have slightly better performance, if you did boolean var = true; (but it probably isn't measurable).

Answer 2

Go for Boolean.TRUE;

The reason

boolean boolVar = Boolean.TRUE;

works is because of autounboxing, a Java 5 feature that allows a wrapper object to be converted to its primitive equivalent automatically when needed. The opposite, autoboxing, is also possible:

Boolean boolVar = true;

Boolean.TRUE is a reference to an object of the class Boolean, on the other hand, true is value of the primitive boolean type. Boolean class is often called "wrapper classes", and are used when you need an object instead of a primitive type.