Learn Java Part 1

Learn Java Part 1

• 1.
  Introduction to Java,Principles, Versions, JDK, Java Compilation Process, Java Is Platform Independent, Java as Platform
• 2.
  • Java isa general-purpose object-oriented computer programming language. • It is intended to let application developers "write once, run anywhere" (WORA), meaning that compiled Java code can run on all platforms that support Java without the need for recompilation. • Java applications are typically compiled to bytecode that can run on any Java virtual machine (JVM) regardless of computer architecture. • Java was originally developed by James Gosling at Sun Microsystems (which has since been acquired by Oracle Corporation) and released in 1995 as a core component of Sun Microsystems' Java platform.
• 3.
  There were fiveprimary goals in the creation of the Java language: 1. It must be "simple, object-oriented and familiar". 2. It must be "robust and secure". 3. It must be "architecture-neutral and portable". 4. It must execute with "high performance". 5. It must be "interpreted, threaded, and dynamic". Major release versions of Java, along with their release dates: 1. JDK 1.0 (January 21, 1996) 2. JDK 1.1 (February 19, 1997) 3. J2SE 1.2 (December 8, 1998) 4. J2SE 1.3 (May 8, 2000) 5. J2SE 1.4 (February 6, 2002) 6. J2SE 5.0 (September 30, 2004) 7. Java SE 6 (December 11, 2006) 8. Java SE 7 (July 28, 2011) 9. Java SE 8 (March 18, 2014)
• 4.
  The Java DevelopmentKit (JDK) is an implementation of either one of the Java SE(Standard Edition), Java EE(Enterprise Edition) or Java ME(Micro Edition) platforms released by Oracle Corporation in the form of a binary product aimed at Java developers on Solaris, Linux, Mac OS X or Windows. The JDK includes a private JVM and a few other resources to finish the recipe to a Java Application. The JDK has as its primary components a collection of programming tools, including: • java – the loader for Java applications. This tool is an interpreter and can interpret the class files generated by the javac compiler. Now a single launcher is used for both development and deployment. The old deployment launcher, jre, no longer comes with Sun JDK, and instead it has been replaced by this new java loader. • javac – the Java compiler, which converts source code into Java bytecode • javadoc – the documentation generator, which automatically generates documentation from source code comments • jar – the archiver, which packages related class libraries into a single JAR file. This tool also helps manage JAR files. • jdb – the debugger • javap – the class file disassembler And many more
• 5.
  Interpreter for LINUX Interpreterfor Windows Interpreter for Windows Java Source Code(For example: Abc.java) Byte Code(For example: Abc.class) Compile(using “javac”) JVM(Java Virtual Machine) Interpret the Byte code using “java” Machine Code Machine Code Machine Code
• 6.
  One design goalof Java is portability, which means that programs written for the Java platform must run similarly on any combination of hardware and operating system with adequate runtime support. This is achieved by compiling the Java language code to an intermediate representation called Java bytecode, instead of directly to architecture-specific machine code. Java bytecode instructions are analogous to machine code, but they are intended to be executed by a virtual machine (VM) written specifically for the host hardware. End users commonly use a Java Runtime Environment (JRE) installed on their own machine for standalone Java applications, or in a web browser for Java applets.
• 7.
  The Java platformis a suite of programs that facilitate developing and running programs written in the Java programming language. The platform is not specific to any one processor or operating system, rather an execution engine (called a virtual machine) and a compiler with a set of libraries are implemented for various hardware and operating systems so that Java programs can run identically on all of them. There are multiple platforms, each targeting a different class of devices: Java Card: A technology that allows small Java-based applications (applets) to be run securely on smart cards and similar small-memory devices. Java ME (Micro Edition): Specifies several different sets of libraries (known as profiles) for devices with limited storage, display, and power capacities. Often used to develop applications for mobile devices, PDAs, TV set-top boxes, and printers. Java SE (Standard Edition): For general-purpose use on desktop PCs, servers and similar devices. Java EE (Enterprise Edition): Java SE plus various APIs useful for multi-tier client–server enterprise applications. The Java platform consists of several programs, each of which provides a portion of its overall capabilities. For example, the Java compiler, which converts Java source code into Java bytecode (an intermediate language for the JVM), is provided as part of the Java Development Kit (JDK). The Java Runtime Environment (JRE), complementing the JVM with a just-in-time (JIT) compiler, converts intermediate bytecode into native machine code on the fly. An extensive set of libraries are also part of the Java platform.