java - How JVM comes in picture? -

java - How JVM comes in picture? -

i know how jvm interprets byte codes machine code,so brings platform independency. but, want know how jvm comes on system?

i. pre-existing executable programme file resides within jre?so, need install jre, jvm programme on system?

or, ii. mean 'once .java file gets compiled, jvm instance gets created?' mean jvm doesn't pre-exist within jre within allocated memory area of jre, mimic/emulate of actual cpu(of host system) gets created @ run-time, known jvm?

please confirm how jvm comes in picture?

iii.also, want know mean 'instance of jvm?

is pre-existing executable programme file resides within jre? so, need install jre, jvm programme on system?

the java runtime environment indeed separate programme needs installed on computer. when jre, jvm (which programs execute).

what mean 'once .java file gets compiled, jvm instance gets created?' mean jvm doesn't pre-exist within jre within allocated memory area of jre, mimic/emulate of actual cpu(of host system) gets created @ run-time, known jvm?

it's virtual machine indeed pre-exist in jre. can have many applications running java on machine @ once, , they're going executed on different instances of jvm. argue compilation may not create new instance of jvm (it might, i'm not certain), executing java application (or same java application multiple times) definitely create new instances of jvm.

java jvm