java reflection instantiate class by name

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Providing a static method that returns a reference to the instance.

Declaring all constructors of the class to be private.

Provide global access to that instance by Ensure that only one instance of the class exists.Ģ. To create a singleton class, we must follow the steps, given below:ġ.

#Java reflection instantiate class by name how to

How to Design/Create a Singleton Class in Java?

#Java reflection instantiate class by name driver

This is the reason why the multi-threaded and database applications mostly make use of the Singleton pattern in Java for caching, logging, thread pooling, configuration settings, and much more.įor example, there is a license with us, and we have only one database connection or suppose if our JDBC driver does not allow us to do multithreading, then Singleton class comes into the picture and makes sure that at a time, only a single connection or a single thread can access the connection. We can use this single object repeatedly as per the requirements. As the object creation will take place only once instead of creating it each time a new request is made. The memory space wastage does not occur with the use of the singleton class because it restricts the instance creation. This often ensures that there is access control to resources, for example, socket or database connection. The primary purpose of a Singleton class is to restrict the limit of the number of object creation to only one. Here, the concept of Lazy initialization is used to write this static method. Write a static method that has the return type object of this singleton class.Remember the key points while defining class as a singleton class that is while designing a singleton class:

Unified Modeling Language (UML) | Sequence Diagrams.

Design Patterns | Set 2 (Factory Method).

Singleton Design Pattern | Implementation.

SDE SHEET - A Complete Guide for SDE Preparation.

Pairwise swap adjacent nodes of a linked list by changing pointers | Set 2.

Pairwise Swap Nodes of a given linked list by changing links.

Pairwise Swap Nodes of a given Linked List.

Swap nodes in a linked list without swapping data.

Remove duplicates from an unsorted linked list.

Remove duplicates from a sorted linked list.

Function to check if a singly linked list is palindrome.

Remove all occurrences of duplicates from a sorted Linked List.

Move all occurrences of an element to end in a linked list.

Implementing Iterator pattern of a single Linked List.

Strategy Pattern | Set 2 (Implementation).

Strategy Pattern | Set 1 (Introduction).

Decorator Pattern | Set 3 (Coding the Design).

The Decorator Pattern | Set 2 (Introduction and Design).

How to prevent Singleton Pattern from Reflection, Serialization and Cloning?.

Java Singleton Design Pattern Practices with Examples.

Java Interview Questions on Constructors.

Private Constructors and Singleton Classes in Java.

Constructor Chaining In Java with Examples.

ISRO CS Syllabus for Scientist/Engineer Exam.

ISRO CS Original Papers and Official Keys.

GATE CS Original Papers and Official Keys.

#Java reflection instantiate class by name code

But wait, what if some customer wants to enforce 8 character password? You have to modify your apex code for this which is not a good idea. You implement the logic, everything works fine and everybody is enjoying your manages package service.

#Java reflection instantiate class by name password

So lets say, you are using a managed package and you want to validate user password to have minimum 6 characters. Use Interface to make it completely dynamic One challenge you will still see, that you need to specify your Class Type in 2nd line, which kind of does not suit our need as we need it completely dynamic. Here is how you can do it: Type t = Type.forName('YourClassName') //Create a type object using class name YourClassName newObj = (YourClassName)t.newInstance() //create a instance using Type object and TypeCast to your class How many of you are aware that after summer 12 release, we can create Apex Class instance dynamically just by using class name? Yes, no need to specify class type to create class instance.