If I create an instance of a class in Java, why is it preferable to call a static method of that same class statically, rather than using this.method()?
I get a warning from Eclipse when I try to call static method staticMethod() from within the custom class's constructor via this.staticMethod().
public MyClass() { this.staticMethod(); }
vs
public MyClass() { MyClass.staticMethod(); }
Can anyone explain why this is a bad thing to do? It seems to me like the compiler should already have allocated an instance of the object, so statically allocating memory would be unneeded overhead.
EDIT:
The gist of what I'm hearing is that this is bad practice mainly because of readability, and understandably so. What I was really trying to ask (albeit not very clearly) was what differences there are at 'compilation', if any, between calling MyClass.staticMethod() or this.staticMethod().
A static method can be called directly from the class, without having to create an instance of the class. A static method can only access static variables; it cannot access instance variables. Since the static method refers to the class, the syntax to call or refer to a static method is: class name. method name.
A static method has two main purposes: For utility or helper methods that don't require any object state. Since there is no need to access instance variables, having static methods eliminates the need for the caller to instantiate the object just to call the method.
You should consider making a method static in Java : 1) If a method doesn't modify the state of the object, or not using any instance variables. 2) You want to call the method without creating an instance of that class.
Instance method vs Static methodStatic methods can't access instance methods and instance variables directly. They must use reference to object. And static method can't use this keyword as there is no instance for 'this' to refer to.
Static methods are not tied to an instance of the class, so it makes less sense to call it from a this
than to call it from Class.staticMethod()
, much more readable too.
MyClass.staticMethod() makes it clear that you are calling a static (non-overrideable) method.
this.staticMethod() misleads the reader into thinking that it is an instance method.
staticMethod() is also on the misleading side (though I normally do it that way).
If you think of people reading your code as unfamiliar with it you tend to try to make the code clearer, and this is a case where the code is clearer by having ClassName.method instead of instance.method.
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