Why we use constructor in java

I am new to OOP. I am still in a learning phase. Why do we need constructors, When we can initialize the values of the properties (variables) by writing a "Initialize function"? Basically why do we write a constructor when we can achieve the same results even by writing a function for initializing the variables? The constructor IS the "Initialize function" Rather than calling two functions object = new Class; object.initialize(); You just call object = new Class(); The logic inside the constructor can be identical to the logic inside the initialize function, but it's much tidier and avoids you naming your function initialize(), me naming mine initialize_variables(), and someone else naming theirs init_vars()... consistency is useful. If your constructor is very large, you may still wish to split variable initialisation into a separate function and calling that function from your constructor, but that's a specific exception to the scenario. This is not really true. In many languages, constructors cannot call other constructors and thus there is a requirement for a separate initialise function that is either called externally or by each overload of the constructor. There are also patterns where objects are constructed up front and initialised on first use. There are also very useful patterns that demand named, static factory methods that call a private or protected constructor. Again, that's an exception to the "standard" where you may wish to use a separate function to init...

I have seen the history of several С# and Java class library projects on GitHub and CodePlex, and I see a trend of switching to factory classes as opposed to direct object instantiation. Why should I use factory classes extensively? I have pretty good library, where objects are created the old-fashioned way - by invoking public constructors of classes. In the last commits the authors quickly changed all of the public constructors of thousands of classes to internal, and also created one huge factory class with thousands of CreateXXX static methods that just return new objects by calling the internal constructors of the classes. The external project API is broken, well done. Why would such a change be useful? What is the point of refactoring in this way? What are the benefits of replacing calls to public class constructors with static factory method calls? When should I use public constructors, and when should I use factories? Factory classes are often implemented because they allow the project to follow the Factories and interfaces allow for a lot more long term flexibility. It allows for a more decoupled - and therefore more testable - design. Here is a non-exhaustive list of why you might go down this path: • It allows you to introduce an • It makes your code more testable as you can mock interfaces • It gives you a lot more flexibility when it comes time to change the application (i.e. you can create new implementations without changing the dependent code) Consider this...

Getters and Setters play an important role in retrieving and updating the value of a variable outside the encapsulating class. A setter updates the value of a variable, while a getter reads the value of a variable. In this tutorial, we'll discuss the problems of not using 2. Life Without Getters and Setters in Java Think about a situation when we want to change the state of an object based on some condition. How could we achieve that without a setter method? • Marking the variable as public, protected, or default • Changing the value using a dot (.) operator Let's look at the consequences of doing this. 3. Accessing Variables Without Getters and Setters Second, since anyone can change the non-private fields from outside the class directly, we cannot achieve immutability. Third, we cannot provide any conditional logic to the change of the variable. Let's consider we have a class Employee with a field retirementAge: public class Employee Here, any client of the Employee class can easily do what they want with the retirementAge field. There's no way to validate the change. Fourth, how could we achieve read-only or write-only access to the fields from outside the class? Out of many, let's cover some of the most important benefits of using getters and setters: • It helps us achieve encapsulation which is used to hide the state of a structured data object inside a class, preventing unauthorized direct access to them • Achieve immutability by declaring the fields as private and ...

Why We Use Constructor in Java? In this section, we will learn why we use a constructor in Java and what is the purpose and need of the constructor. Along with this, we will also see the types of the constructor. In Java, the constructor is similar to the method. The property of the constructor is that it must have the same name as the class name. It has no return type. We do not require to call the constructor manually. It automatically invokes implicitly during the instantiation. In other words, a constructor is a method that is called at runtime during the object creation by using the new operator. The JVM calls it automatically when we create an object. When we do not define a constructor in the class, the default constructor is always invisibly present in the class. There are the following reasons to use constructors: • We use constructors to initialize the object with the default or initial state. The default values for primitives may not be what are you looking for. • Another reason to use constructor is that it informs about dependencies. In other words, using the constructor, we can request the user of that class for required dependencies. • We can find out what it needs in order to use this class, just by looking at the constructor. In short, we use the constructor to initialize the instance variable of the class. Types of Constructors There are two types of constructors in Java: • Parametrized Constructor • Default Constructor Parameterized Constructor As the na...

/** * This program is used to show the use of parameterized constructor. * @author W3spoint */ public class ParameterizedConstructor Output

Advertisements It has the same name as of the class. Why do we need Constructors ? Whenever we create an object in Object Oriented Methodology, we first need initialize its member variables. For example, we have a class Game with name and level as its member variables. Now suppose we created an object of this class Game, but forgot to initialize it. In that case its name and levels for this object will be garbage and will give undesired result when we call other member functions that uses them. Frequently Asked: • As initialization is must for an object before using it, therefore in Java language support for Constructors has been added. Whenever we create a new object in Java, first of all its Constructor is called to initialize its value. [showads ad=inside_post] For example, we have a class Game, lets create an object of it, Game obj = new Game(); Before this new object is assigned to reference obj, its constructor will be called internally. Lets see the complete example, package thispointer.java.examples.constructors; public class Game To provide the best experiences, we and our partners use technologies like cookies to store and/or access device information. Consenting to these technologies will allow us and our partners to process personal data such as browsing behavior or unique IDs on this site and show (non-) personalized ads. Not consenting or withdrawing consent, may adversely affect certain features and functions. Click below to consent to the above or make gra...

No, a constructor cannot be synchronized in Java. The JVM ensures that only one thread can invoke a constructor call at a given point in time. That is why no need to declare a constructor as synchronized andit is illega lin Java. However, we can use synchronized blocks inside a constructor. If we are trying to put a synchronized keywordbefore a constructor, the compiler says that " error: modifier synchronized not allowed here". Example public class SynchronizedConstructorTest Output SynchronizedConstructorTest.java:3: error: modifier synchronized not allowed here public synchronizedSynchronizedConstructorTest() { ^ 1 error