Java Buzzwords/Features

1. Simple
   • Java was designed to be easy for a professional programmer to learn and use effectively.
   • It's simple and easy to learn if you already know the basic concepts of Object Oriented Programming.
   • If you are an experienced C++ programmer, moving to Java will require very little effort. Because Java inherits the C/C++ syntax and many of the object-oriented features of C++, most programmers have little trouble learning Java.
   • Java has removed many complicated or rarely-used features of C++, for example, pointers, operator overloading, etc.
   • Java was simple till Java 1.4. Later many new features were added to the language to make it powerful (but complex too).
2. Object Oriented
   • Java is a object-oriented programming language.
   • Almost the "Everything is an Object" paradigm. All program code and data reside within objects and classes.
   • The object model in Java is simple and easy to extend.
   • Java comes with an extensive set of classes, arranged in packages that can be used in our programs through inheritance.
   • The basic concepts of OOPs are:
     • Object
     • Class
     • Abstraction
     • Encapsulation
     • Inheritance
     • Composition
     • Polymorphism
3. Distributed
   • Java is designed to create distributed applications connected over the network.
   • Java applications can access remote objects on the Internet as easily as they can do in the local system.
   • Java is designed for the distributed environment of the Internet. It handles TCP/IP protocols.
4. Compiled and Interpreted
   • Usually, a computer language is either compiled or interpreted. Java combines both this approach and makes it a two-stage system.
   • Compiled: Java enables the creation of cross-platform programs by compiling them into an intermediate representation called Java Bytecode.
   • Interpreted: Bytecode is then interpreted, which generates machine code that can be directly executed by the machine/CPU.
5. Robust
   • It provides many features that make the program execute reliably in a variety of environments.
   • Java is a strictly typed language. It checks code both at compile time and runtime.
   • Java takes care of all memory management problems with garbage collection.
   • Exception handling captures all types of serious errors and eliminates any risk of crashing the system.
6. Secure
   • When a Java Compatible Web browser is used, downloading applets can be done safely without fear of infection or malicious intent.
   • Java achieves this protection by confining a Java program to the Java execution environment and not allowing it to access other parts of the computer.
7. Architecture Neutral
   • Java language and Java Virtual Machine helped in achieving the goal of WORA - Write (Compile) Once Run Anywhere.
   • Java byte code is interpreted and converted into CPU machine code/native code. So Java byte code can execute on any CPU architecture (on which JVM is available) like x86, SPARC, PPC, MIPS, etc.
8. Portable
   • Java is portable because of the Java Virtual Machine (JVM). The JVM is an abstract computing machine that provides a runtime environment for Java programs to execute.
   • The JVM provides a consistent environment for Java programs to run on, regardless of the underlying operating system. Java program can be written on one device and run on any other device with a JVM installed, without any changes or modifications.
9. High Performance
   • Java performance is high because of the use of bytecode.
   • The bytecode is used so that it can be efficiently translated into native machine code by JIT compiler (in JVM).
10. Multithreaded
    • Multithreaded Programs handle multiple tasks simultaneously (within a process), which is helpful in creating interactive, networked programs.
    • Java supports multi-process/thread communication and synchronization.
11. Dynamic
    • Java is capable of linking in new class libraries, methods, and objects.
    • Java classes have run-time type information (reflection) that is used to verify and resolve accesses to objects/members at runtime. This makes it possible to dynamically link code in a safe and expedient manner.

CLASSPATH

• CLASSPATH: Contains a set of directories separated by ; (Windows) or : (Linux).
  • Java's environment variable by which one can inform Java compiler, application launcher, JVM and other Java tools about the directories in which Java classes/packages are kept.
  • CLASSPATH variable can be modified using "set" command (Windows) or "export" command (Linux).
• Set/Modified using:
  • Windows: set CLASSPATH=\\\\path\\\\to\\\\set\\\\%CLASSPATH%
  • Linux: export CLASSPATH=/path/to/set:$CLASSPATH
• Display current CLASSPATH:
  • Windows: set CLASSPATH
  • Linux: echo $CLASSPATH
• Compilation and Execution (source code in "src" directory and .class file in "bin" directory)
  • terminal> cd \path\of\src directory
  • terminal> javac -d ..\bin Program.java
  • terminal> set CLASSPATH=..\bin
  • terminal> java Program

Console Input/Output

• Java has several ways to take input and print output. Most popular ways in Java 8 are given below: