50 Senior Java Developer Interview Questions (ANSWERED) To Know in 2020

 

Q1: 
What is JVM? Why is Java called the “Platform Independent Programming Language”?


Answer

A Java virtual machine (JVM) is a process virtual machine that can execute Java bytecode. Each Java source file is compiled into a bytecode file, which is executed by the JVM. Java was designed to allow application programs to be built that could be run on any platform, without having to be rewritten or recompiled by the programmer for each separate platform. A Java virtual machine makes this possible, because it is aware of the specific instruction lengths and other particularities of the underlying hardware platform. know more java training

Q2: 
What is Spring?


Answer

Spring is an open source development framework for enterprise Java. The core features of the Spring Framework can be used in developing any Java application, but there are extensions for building web applications on top of the Java EE platform. Spring framework targets to make J2EE development easier to use and promote good programming practice by enabling a POJO-based (Plain Old Java Object) programming model.

Q3: 
What is the Difference between JDK and JRE?


Answer

  • The Java Runtime Environment (JRE) is basically the Java Virtual Machine (JVM) where your Java programs are being executed. It also includes browser plugins for applet execution.

  • The Java Development Kit (JDK) is the full featured Software Development Kit for Java, including the JRE, the compilers and tools (like JavaDoc, and Java Debugger), in order for a user to develop, compile and execute Java applications.know more java training

  • Q4: 
    What are Spring beans?


    Answer

    The objects that form the backbone of your application and that are managed by the Spring IoC container are called beans. A bean is an object that is instantiated, assembled, and otherwise managed by a Spring IoC container. These beans are created with the configuration metadata that you supply to the container, for example, in the form of XML <bean/> definitions.

  • Q5: 
    What are benefits of using Spring?


    Answer

    Following is the list of few of the great benefits of using Spring Framework:

    • Lightweight − Spring is lightweight when it comes to size and transparency. The basic version of spring framework is around 2MB.
    • Inversion of control (IOC) − Loose coupling is achieved in spring using the technique Inversion of Control. The objects give their dependencies instead of creating or looking for dependent objects.
    • Aspect oriented (AOP) − Spring supports Aspect oriented programming and enables cohesive development by separating application business logic from system services.
    • Container − Spring contains and manages the life cycle and configuration of application objects.
    • MVC Framework − Spring's web framework is a well-designed web MVC framework, which provides a great alternative to web frameworks such as Struts or other over-engineered or less popular web frameworks.know more java training
    • Transaction Management − Spring provides a consistent transaction management interface that can scale down to a local transaction (using a single database, for example) and scale up to global transactions (using JTA, for example).
    • Exception Handling − Spring provides a convenient API to translate technology-specific exceptions (thrown by JDBC, Hibernate, or JDO, for example) into consistent, unchecked exceptions.know more java training
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