Java Components

Java language has large number of tools called as components. These tools are required while compiling and running the java programs.

What are the components of Java?

Java contains the large number of tools to develop an application on either internet or on desktop application.

JVM and JDK are necessary for running every java application.

Java Virtual Machine - JVM

Java Compiler translates source code into machine code for specific computer. But java compiler produces an intermediate code known as Byte code.

The java virtual machine is existing in the computer memory. It is simulated computer within the computer and performs all major functions of real computer.

The output produced by the java compiler is not executable code. It is byte code, which is highly optimized set of instructions executed by java run time system called JVM.

How JVM Works?

The virtual machine code generated by java interpreter is not portable, but it acts as an intermediary between the virtual machine and real machine.

The java API acts as an intermediary between the user programs and virtual machine which turn acts as the intermediary between the operating system and java object framework.

By translating a java program into byte code makes it easier to run the program on a variety of environment thus JVM provides the most convenient way of making potable program. The byte code requires the JVM for execution it makes the secure. This is because the JVM can control and prevent the programs from generating side effects of outside system.

When program is compiled and then interpreted, the processing time is reduced because the byte code is highly optimized set of instructions and JVM executes them much faster.

Java Developement Kit - JDK

Java development environment includes a number of development tools, classes and methods. It is a part of the system known as Java development kit (JDK). Classes and methods are part of application programming interface (API).

What are the JDK tools?

if you want to see the all JDK Tools then you have to navigate into your computer to below location

goto C:\Program Files(86)\Java\jdk1.x.x\bin

You will be able to see below list of all JDK Tools

Some most common JDK tools

1. appletviewer : this tool can be used to run and debug Java applets without a web browser.
   a pre-created applet can be viewed using applet viewer enables us to run java applets (by any browser).
   Ex- c:\> appletviewer
2. javac : javac is java compiler which executes the program created by text editor with extension .java javac converts the .java file into a .class file.
   Ex- c:\> javac coder.java
3. java : java is java interpreter which is used to execute a compiled java .class file. The byte code created as a result of compilation is interpreted.
   Ex- c:> java < class-filename >
4. JConsole : Java Monitoring and Management Console.
5. jmc : Java Mission Control
6. javap : javap is java disassembler which is used to convert byte code files into a program, description.
7. javah : javah is used for producing header files for use with native methods of C and C++
8. javadoc : javadoc is used for creating HTML formatted documents for java source code files.
9. jdb : jdb is java debugger, which helps us to find errors in our programs.