JVM (Java Virtual Machine) is a
platform - independent execution environment that converts Java bytecode
into machine language and executes it.
JVM -Java Virtual
JVM consist of following components:-
1) Byte-code verifier: - It verify the
byte-code ,it check's for unusual code.
2) Class Loader: - After verifying Class Loader will load the byte-code
into the memory for execution.
3) Execution engine: -
It further consists of 2 parts :-
a) Interpreter: - It interpretsthe code& run.
b) JIT (Just-in-Time Interpreter)
JVM Hotspot defines when to use Interpreter or JIT.
4) Garbage Collector: - It periodically check for the object on heap ,
whose link is broken
So it can collect the garbage from Heap.
5) Security Manager: - It constantly monitorsthe code. It is
2nd level of security.[1st level is Byte-codeverifier].
JVM stands forJava Virtual
Machine. As the name indicates, it does not a real hardware machine but a
software layer which resembles a hardware platform. JVM helps to run java
programs on different Operating system platforms. The JVM will be different
for different Operating Systems i.e. there will be separate JVM for
Linux. Now I am going to explain how Java achieves platform independents
with the help of JVM. We can write the java program on any platform. The
source program is then converted to byte code using a Java compiler. The
compiler will be different for different platforms. The byte code can be
executed on any platform where there exist JVM.