Core Java Interview Question

Core Java Interview Questions and Answers# What is Java?Java is the high-level, object-oriented, robust, secure programming language, platform-independent, high performance, Multithreaded, and portable programming language. It was developed by James Gosling in June 1991. It can also be known as the platform as it provides its own JRE and API.# What are the differences between C++ and Java?· C++ is platform-dependent.Java is platform-independent.· C++ is mainly used for system...
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Core Java Interview Questions and Answers# What is Java?Java is the high-level, object-oriented, robust, secure programming language, platform-independent, high performance, Multithreaded, and portable programming language. It was developed by James Gosling in June 1991. It can also be known as the platform as it provides its own JRE and API.# What are the differences between C++ and Java?· C++ is platform-dependent.Java is platform-independent.· C++ is mainly used for system programming.Java is mainly used for application programming. It is widely used in window, web-based, enterprise and mobile applications.· C++ supports multiple inheritance.Java doesn't support multiple inheritance through class. It can be achieved by interfaces in java.· C++ supports pointers. You can write pointer program in C++.Java supports pointer internally. But you can't write the pointer program in java. It means java has restricted pointer support in java.# What do you understand by Java virtual machine?Java Virtual Machine is a virtual machine that enables the computer to run the Java program. JVM acts like a run-time engine which calls the main method present in the Java code. JVM is the specification which must be implemented in the computer system. The Java code is compiled by JVM to be a Bytecode which is machine independent and close to the native code.# What is the difference between JDK, JRE, and JVM?JVMJVM is an acronym for Java Virtual Machine; it is an abstract machine which provides the runtime environment in which Java bytecode can be executed. It is a specification which specifies the working of Java Virtual Machine. Its implementation has been provided by Oracle and other companies. Its implementation is known as JRE.JVMs are available for many hardware and software platforms (so JVM is platform dependent). It is a runtime instance which is created when we run the Java class. There are three notions of the JVM: specification, implementation, and instance.JREJRE stands for Java Runtime Environment. It is the implementation of JVM. The Java Runtime Environment is a set of software tools which are used for developing Java applications. It is used to provide the runtime environment. It is the implementation of JVM. It physically exists. It contains a set of libraries + other files that JVM uses at runtime.JDKJDK is an acronym for Java Development Kit. It is a software development environment which is used to develop Java applications and applets. It physically exists. It contains JRE + development tools. JDK is an implementation of any one of the below given Java Platforms released by Oracle Corporation:Standard Edition Java PlatformEnterprise Edition Java PlatformMicro Edition Java Platform# Name some OOPS Concepts in Java?Java is based on Object Oriented Programming Concepts, following are some of the OOPS concepts implemented in java programming.AbstractionEncapsulationPolymorphismInheritanceAssociationAggregationComposition# What do you mean by platform independence of Java?Platform independence means that you can run the same Java Program in any Operating System. For example, you can write java program in Windows and run it in Mac OS.# What is JVM and is it platform independent?Java Virtual Machine (JVM) is the heart of java programming language. JVM is responsible for converting byte code into machine readable code. JVM is not platform independent, thats why you have different JVM for different operating systems. We can customize JVM with Java Options, such as allocating minimum and maximum memory to JVM. It's called virtual because it provides an interface that doesn't depend on the underlying OS.