Core Java interview

In this post, we will see about Inheritance in java. It is one of the OOPs principles apart from Abstraction, encapsulation and polymorphism. Introduction The word Inheritance is quite familiar with everyone. In common terms, the word means the bequeathing of property and characteristics from generation to generation. For example, the property or characteristics of […]

Java 5 has introduced new framework called Executor Framework for managing threads.We have already seen before how to create a thread. If you have noted, we need to create an object of thread class using new Thread(runnableObject), so we need to create thread object for each task.Imagine a situation where you have thousands of task […]

In this tutorial, we will learn about Executor’s newSingleThreadExecutor factory method. In the last tutorial, I have shared an introduction to ThreadPoolExecutor. If you are not aware of concepts of ThreadPoolExecutor, you should go through that first. Executor’s newSingleThreadExecutor factory method : This method returns thread pool executor which executes one task at a time.If […]

There are multiple ways to schedule a task in java. We have already Java timer to schedule a task but the problem with timers task is that you can execute one task at a time.So if the current task takes longer subsequent job will be delayed. In this scenario, you can use Java ScheduledThreadPoolExecutor.This class […]

In this tutorial, we will see about Polymorphism in java. Polymorphism in java is one of core Object oriented programming concepts with Abstraction, encapsulation, and inheritance. Polymorphism means one name many forms. In Java, polymorphism can be achieved by method overloading and method overriding. There are two types of polymorphism in java. Compile time polymorphism. Run […]

In this tutorial, we will learn about Executor’s newFixedThreadPool factory method. In the last tutorial, I have shared an introduction to ThreadPoolExecutor. If you are not aware of concepts of ThreadPoolExecutor, you should go through that first. Executor’s newFixedThreadPool factory method : This method returns ThreadPoolExecutor whose maximum size(let’s say n threads) is fixed.If all […]

Encapsulation in java is the process of binding related data(variables) and functionality(methods) into a single unit called class. Encapsulation can be achieved by using access modifier such as public, private, protected or default, so your class will be safe from unauthorized access by others and will be simple to maintain. We can create fully encapsulated […]

1. Introduction Abstraction is a concept of exposing only essential details and hiding implementation details. It is one of the essential OOPs concept apart from encapsulation, inheritance and polymorphism. Abstraction retains only information which is most relevant for the specific purpose. For example: ArrayList stores objects sequentially as list, and you can use the add() method […]

In this post, we are going to see difference between notify and notifyall in java. notify(): When you call notify method on the object, it wakes one of thread waiting for that object. So if multiple threads are waiting for an object, it will wake of one of them. Now you must be wondering which […]