Why static methods

No abstraction in-between makes that code hard to test. Explicit dependencies injected either as constructor parameters or method parameters fix these two issues. They allow you to introduce abstractions between the caller and the callee and therefore enable unit testing. They also make the dependency graph clear and easy to reason about.

Explicit dependencies also help you to narrow down the scope of those dependencies, making them available for specific classes and not the entire code base.

The narrower the scope of something, the easier it is to understand. The final epiphany comes when you learn about functional programming. The main idea of functional programming is avoidance of hidden inputs and outputs, such as:. In functional programming, all functions must have explicit inputs and outputs I call this practice method signature honestry. This practice leads to code that is extremely easy to understand and maintain. July 29, at AM Satyam said December 6, at PM Satyam said Great article December 6, at PM Anonymous said January 20, at PM Anonymous said April 11, at AM Dhanashree said August 2, at AM.

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How to get current URL, parameters and Hash tag us How ClassLoader Works in Java? Using PowerMock there are few scenarios, if any, where you find method dependencies which cannot be mocked. You can unit test statics using PowerMock, however you'll soon find you run out of Permgen space done that, got the T-shirt , and its still nasty. Seriously, the worst code I've ever seen came from an embedded developer's use of statics and in most cases we were stuck with it, forever, and adding more code just locked us into the unmodifiable monolith even more tightly.

I can understand the difficulty of testing static methods that depend on static state. But when you're testing stateless static methods like Math. I would say a simple rule of thumb is: if you'd ever have any reason to mock out the procedural logic, then don't put it in a static method.

I've never had a reason to mock out Arrays. Show 8 more comments. Jonah 14 14 silver badges 25 25 bronze badges. Zishan Zishan 8 8 silver badges 12 12 bronze badges. Kevin Sylvestre Kevin Sylvestre You should use static methods if don't need object's state manipulations. If you apply static keyword with any method, it is known as static method. A static method belongs to the class rather than object of a class.

A static method invoked without the need for creating an instance of a class. A static method can be accessed just using the name of a class dot static name. Josi 7 7 silver badges 12 12 bronze badges. IndianProgrammer IndianProgrammer 5 5 silver badges 14 14 bronze badges. If any non-static fields of a class are used you must use a non-static method. Carsten Carsten 3, 4 4 gold badges 30 30 silver badges 48 48 bronze badges. Clear, short and simple answer. Here is a useful example: A car class might have an instance method called Accelerate.

Charlie Seligman Charlie Seligman 3, 5 5 gold badges 52 52 silver badges 85 85 bronze badges. This does not give any rationale for the design of a program. Sagar Sagar 61 2 2 silver badges 7 7 bronze badges. Keeping state in static variables is a bad thing to do for many reasons - like multi-threading safety, debugging, data-encapsulation..

Good example would be an utility class, for say math calculations. Static: Obj. Finbarr Finbarr 29k 12 12 gold badges 60 60 silver badges 92 92 bronze badges. Vaishak Suresh Vaishak Suresh 5, 9 9 gold badges 38 38 silver badges 64 64 bronze badges. Look where I came while googling Java noobie questions!

It's a small world :- — Deepak. Deepak small world indeed : — Vaishak Suresh. Echilon 9, 28 28 gold badges silver badges bronze badges. Manju Yadav Manju Yadav 41 1 1 bronze badge. Static methods can be used if One does not want to perform an action on an instance utility methods As mentioned in few of above answers in this post, converting miles to kilometers, or calculating temperature from Fahrenheit to Celsius and vice-versa.

Consider below 1. Amit Kaneria Amit Kaneria 4, 2 2 gold badges 30 30 silver badges 35 35 bronze badges. We use static method when we no need to be invoked method using instance. I found a nice description, when to use static methods: There is no hard and fast, well written rules, to decide when to make a method static or not, But there are few observations based upon experience, which not only help to make a method static but also teaches when to use static method in Java.

You should consider making a method static in Java : If a method doesn't modify state of object, or not using any instance variables. You want to call method without creating instance of that class. Jake N Jake N 41 1 1 bronze badge. 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.

For the state that is shared by all instances of the class, like a counter. All instance must share the same state. Methods that merely use that state should be static as well. A common use for static methods is to access static fields. Not all combinations of instance and class variables and methods are allowed: Instance methods can access instance variables and instance methods directly.

Instance methods can access class variables and class methods directly. Class methods can access class variables and class methods directly. Class methods cannot access instance variables or instance methods directly—they must use an object reference. Also, class methods cannot use the this keyword as there is no instance for this to refer to. Ravindra babu Ravindra babu Avoid returning Whenever you require to explore the constructor You could turn the String into a As you might know, static here is Override annotation is used when we override You can achieve that concisely in Java: Random Already have an account?

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