Java Virtual Machine

JIT(Just-In-Time)

Just-In-Time(JIT) is a heart of JVM. Mainly use to compiles Bytecodes to Machine codes at runtime. At runtime JIT Compiler performs some optimization on that given application codes. It improves the performance of the particular application codes and functionally takes less time for exection of the codes. Below the diagram represent how to the bytecodes converted to the machine codes at runtime through the JIT compiler.

JRE( Java Runtime Environment )

Java Runtime Environment is the subset of Java Development Kit(JDK). When we install Java Development Kit(JDK),Java Runtime Environment(JRE) is also installed automatically. Java Runtime Environment(JRE) software is available as a separate pack. Therefore we can install Java Runtime Environment(JRE) alone. Java Runtime Environment has only Java Virtual Machine(JVM). Hence using Java Runtime Environment(JRE) can only execute already developed application programs.

JDK(Java Development Kit)

From below diagram we can see JDK has both compiler & JVM. The Java Development Kit(JDK) is a collection of programs to support developers compile,run and debug the java programs. Because of this by using JDK , We can develop,compile and execute new Java Applications and also we can modify,compile and execute already developed applications. The JDK comes with a collection of tools that are used for developing and running Java programs.
Below mention the tools are include with JDK and what is the functions of these tools.Details discription given

Tool ―――― Functions

java ⟹ The loader for Java applications. This tool is an interpreter and can interpret the class files generated by the javac compiler.
javac ⟹ The compiler, which converts source code into Java bytecode.
jar ⟹ The archiver, which packages related class libraries into a single JAR file.
javadoc ⟹ The documentation generator, which automatically generates documentation from source code comments.
javah ⟹ The C header and stub generator, used to write native methods.
jdb ⟹ The Java debugger.
jps ⟹ The process status tool, which displays process information for current Java processes.
javap ⟹ The class file disassembler
appletviewer ⟹ This tool can be used to run and debug Java applets without a web browser.

Diagram Represntation

Previous Page Next Page