Java Terms

Overview

• Java converts the basic instructions to the ByteCode (0,1)(which is common irrespective of operating system)
• conversion bytecode to windows Instructions is through(windows JVM –> piece of software) because windows instructions can only understand normal language (or) instructions specific to that OS.
• ex: windows instructions, linux instructions.
• we get bytecode when Java code is compiled to run the program on the specific operating system which is called as Execution.
• During Execution, we use JVM to convert Bytecode to windows specific instructions.
• JVM(Java Virtual Machine) –> runs java byteCode.
• JRE(Java Runtime Environment) –> JVM+libraries+other components. Application users use JRE (user who uses developed app–using a website)
• JDK(Java Development Kit) –> JVM+Compilers+Debuggers. Application Developers use JDK
• In JDK we have 2 parts –> Java compiler(javac.exe and it is an engine which converts source code of program to bytecode) , Interpreter(java.exe and it is an engine which is used to execute byte code of java application)
• Libraries: A java library is just a collection of classes that have been writtern by somebody else already. you download those classes and tell your computer about them and then you can use those classesin your code.
• Standard libraries: most used libraries which contains a list of libraries to make work easier.
• Built-in-libraries: java provides rich set of libraries and its standard library is powerful which contains java.*, java.util, java.lang., etc..
• Procedural/structured programming: Thinking in terms of procedures/methods/functions
• Object oriented Proggraming: Thinking in terms of objects(template), class(instance), data(state), action(method behaviour).
• Serialization: Serialization is the conversion of an object to a series of bytes, so that the object can be easily saved to persistent storage( any data storage device that retains data after power to that device is shut off) or streamed across a communication link.
• Deserialization: converting into a replica of the original object.