java,linux,oop , Java memory model for static methods
Java memory model for static methods
Question:
Tag: java,linux,oop
I come from operating systems and background of C where the world is simple when code is compiled. Need to deal and understand stack, heap text section etc.
When I started learning Java(I do know about JVM and garbage collector), I got amused by static methods. As per my understanding all the instances of a class do get created in the heap and then do get cleaned. However, for a static method, you don't need an instance of the class.
So, can some one please explain how non static methods and static methods differ in memory model. Do both of them reside in the text section of the memory. Or I am messing up things completely.
Thanks
Answer:
In Java, the bytecode for the classes (and that includes their methods, both static and instance) is part of the heap (usually in a special "permanent generation" section for long-lived objects).
Classes can be garbage-collected, too, but this usually does not happen much (only when the class was loaded from a non-system classloader and that whole classloader becomes obsolete, for example when a web application is unloaded).
However, for a static method, you don't need an instance of the class.
Right. But all methods are part of the class definition and loaded together when the class is loaded. Even if you never make an instance of a class, the code for all instance methods will be loaded into heap memory.
And then there is JIT compilation to native code: With Hotspot, the bytecode for frequently used methods is compiled further into native machine code. The result of that does go somewhere outside of the heap into native memory, and that only happens for methods that are actually being used (static or not).
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