Java Tutorials

Java is a most widely used server side object oriented programming language.

Features of Java

  • Simple:
    • User friendly syntax based on C++
    • It has Automatic Garbage Collection
    • It has Rich set of APIs
    • Removed confusing features – explicit pointers, operator overloading, multiple inheritance, etc
  • Object-oriented:
    • In Java, we organize the software as a combination of different types of objects that incorporates both data and behaviour.
    • Based on the concept of Objects, Class, Inheritance, Polymorphism, Abstraction, Encapsulation
  • Platform Independent:
    • Java provides software-based platform. It has two components:
      • JRE (Runtime Environment)
      • API (Application Programming Interface)
    • Java code is compiled by the compiler and converted into bytecode. This bytecode is a platform-independent. Can run on many platforms – Windows, Linux, Mac, etc.
  • Secured:
    • No explicit pointer
    • JVM – java Programs run inside virtual machine sandbox
    • Classloader – adds security by separating the package for the classes of the local file system from those that are imported from network sources.
    • Bytecode Verifier – checks the code fragments for illegal code that can violate access right to objects.
    • Security Manager – determines what resources a class can access such as reading and writing to the local disk.
    • More – developers can add extra security through SSL, JAAS, Cryptography etc.
  • Robust:
    • Good memory management – automatic garbage collection.
    • No pointers – increses security.
    • Exception handling – increses robustness against errors.
    • Strongly typed – every variable must be declared with a data type.
    • Statically typed – type checking of variables is performed at compile time.
  • Architecture-Neutral:
    • There is no implementation dependent features. e.g. size of primitive types is fixed.
  • Portable:
    • Write Once and Run Anywhere.
  • Interpreted:
    • Java is compiled to bytecodes, which are interpreted by a Java run-time environment.
    • The interpreter reads bytecode stream then execute the instructions.
  • High-Performance:
    • Uses ByteCode
    • Just-In-Time (JIT)
    • Garbage collector
  • Distributed:
    • We can create distributed applications in java. RMI and EJB are used for creating distributed applications.
    • We may access files by calling the methods from any machine on the internet.
  • Multi-threaded:
    • A thread is like a separate program, executing concurrently. We can write Java programs that deal with many tasks at once by defining multiple threads.
    • The main advantage of multi-threading is that it doesn’t occupy memory for each thread. It shares a common memory area.
    • Threads are important for multi-media, Web applications etc.
  • Dynamic:
    • Dynamic Compilation (JIT) – Implementations to gain performance during program execution. The machine code emitted by a dynamic compiler is constructed and optimized at program runtime, the use of dynamic compilation enables optimizations for efficiency.
    • Load on Demand – Loads in classes as they are needed, even from across the network.
    • Dynamic memory allocation – All Java objects are dynamically allocated.
    • Dynamic Polymorphism – Compiler doesn’t know which method to be called in advance. JVM decides which method to called at run time.

Core Java Tutorials

Java Sorting Programs