Java has been a perennial contributor to the software development domain. It is not only necessary to learn and master Java skills but also to practice these skills in real-time. Who does not want to ace the entire process of selection process for job placements? You anyways have enough to do. We bring you, some of the most sought-after Java Interview Questions that will help you ace major interview processes and help test your skills and knowledge at their absolute.
Garbage collection java
Java garbage collection is the process by which Java programs perform automatic memory management. When a computer runs a program, it needs to allocate system resources to the program while it's running. This is where memory comes in. The processor needs instructions to execute on the stack, and the heap holds strings, objects, and any other dynamic data that are created during program execution.
Reflection API in java
Reflection is an API that is used to examine or modify the behaviour of methods, classes, interfaces at runtime. The required classes for reflection are provided under java. lang. reflect package . Reflection can be used to write tools that manipulate classes and objects, such as introspection, weaving and bytecode manipulation.
Java ClassLoader
Class loaders are Java objects responsible for loading classes into the JVM (Java Virtual Machine). They're also part of the JRE (Java Runtime Environment) and take on the duties of locating and loading class files provided by executing applications.
Java Logging API
The Logging API provides services for capturing information such as security failures, configuration errors, performance bottlenecks, and/or bugs in the application or platform. These logs are used to perform troubleshooting and to maintain application availability through the identification and resolution of problems. The underlying implementation is provider-configurable so that you can use multiple underlying logging implementations including JDK logging and log4j.
Some of Java interview Questions for Experienced
What is enumeration in Java?
An enumeration is a list of named constant. In Java, enumeration defines a class type. An enumeration can have constructors, methods and instance variables. It is created using enum keyword. Each enumerates constants are public, static as well as final by default. Even though enumeration defines class type and have constructors, you do not initiate an enum using new enums. Enumeration variables are used and declared same way as you do primitive variable
What is inheritance in Java?
Inheritance is an important feature of java. As java is a pure object oriented language so to achieve reusability of code, we use inheritance. Inheritance helps us to extend the existing class and create the new class with inbuilt features. For example: if we have a class calculator having methods calculate() and calculateTax() then with in that class we can create more classes say SimpleCalculator and ScientificCalculator which will inherit the methods from calculator. Here SimpleCalculator will not have method calculateTax() but it will inherit method calculate().
What is abstraction in Java?
The word abstraction is used in a general sense. There are two types — data abstraction and function abstraction. Data Abstraction: In this abstraction, the emphasis lies on hiding data from the users of the program. It is used for grouping different similar types of data together. Function Abstraction: In this abstraction, the main focus lies on grouping the multiple functions together. We can re-use these functions in specifications.
What is package in java?
A package in Java is a collection of related classes. A class is placed in a package to avoid name conflicts and to improve code organisation. Java packages consist of classes, subpackages and subclasses. Packages can be hierarchical. Packages are divided into two categories:
What is method in java?
Methods are blocks of code that only execute when they are called. In Java, a method is also referred to as a function. The method can take parameters and perform actions on data. Your programs will be more efficient by using methods rather than repeating chunks of code in several different places in your source code.
What is string in java?
String is one of the basic and built-in java class which represents a sequence of characters. It is widely used in any programming language. String can be considered as one of the most widely used data type, data structure, and components in Java. Let us see some of the methods to convert String to other data types like int, float, double etc
What is garbage collection in java?
Java garbage collection is an automatic process. The programmer does not need to explicitly mark objects to be deleted. The garbage collection implementation lives in the JVM. Each JVM can implement garbage collection however it pleases; the only requirement is that it meets the JVM specification. Although there are many JVMs, Oracle’s HotSpot is by far the most common. It offers a robust and mature set of garbage collection options.
Also Read: Types of communication
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It is a high-level programming language developed by James Gosling in Sun Microsystem in 1995.
Java is a fast, secure and reliable language used for many games, devices and applications.
Portable – Java program gets converted into Java Byte Codes that can be executed on any platform without any dependency.
Platform independent – java works on “write once and run anywhere” as it supports multiple platforms like Windows, Linux, Mac, Sun Solaris, etc.
Interpreted – java compiler converts the codes into Java Byte Codes which are then interpreted and executed by Java Interpreter.
An object consists of methods and class which depict its state and perform operations.
