Where are static methods and static variables stored in Java

Question

For example   class A       static int i 0      static int j      static void method               static k 0  can t use static for local variables only final is permitted           static int L            Where will these variables be stored in Java  in heap or in stack memory  How are they stored

User · Answer

In real world or project we have requirement in advance and needs to create variable and methods inside the class , On the basis of requirement we needs to decide whether we needs to create

Local ( create n access within block or method constructor)
Static,
Instance Variable( every object has its own copy of it),

=>2. Static Keyword we will used with variable which going to same for particular class throughout for all objects, e.g in selenium : we decalre webDriver as static=> so we do not need to create webdriver again and again for every test case= Static Webdriver driver(but parallel execution it will cause problem but thats another case); then, Real world scenario=>If India is class then, flag, money would be same every indian so we might take as static. Anatoher example: utility method we always declare as static b'cos it will be used in different test cases. Static stored in CMA( PreGen space)=PreGen (Fixed memory)changed to Metaspace after Java8 as now its growing dynamically

User · Answer

As static variables are class level variables  they will store   permanent generation   of heap memory  Please look into  this for more details of JVM  Hoping this will be helpful

User · Answer

In addition to the Thomas s answer   static variable are stored in non heap area which is called Method Area

User · Answer

This is a question with a simple answer and a long-winded answer   The simple answer is the heap  Classes and all of the data applying to classes  not instance data  is stored in the Permanent Generation section of the heap   The long answer is already on stack overflow   There is a thorough description of memory and garbage collection in the JVM as well as an answer that talks more concisely about it

User · Answer

Prior to Java 8   The static variables were stored in the permgen space also called the method area    PermGen Space is also known as Method Area  PermGen Space used to store 3 things   Class level data  meta-data  interned strings static variables   From Java 8 onwards  The static variables are stored in the Heap itself From Java 8 onwards the PermGen Space have been removed and new space named as MetaSpace is introduced which is not the part of Heap any more unlike the previous Permgen Space  Meta-Space is present on the native memory  memory provided by the OS to a particular Application for its own usage  and it now only stores the class meta-data   The interned strings and static variables are moved into the heap itself   For official information refer   JEP 122 Remove the Permanent Gen Space

User · Answer

Static methods  in fact all methods  as well as static variables are stored in the PermGen section of the heap  since they are part of the reflection data  class related data  not instance related    Update for clarification    Note that only the variables and their technical values  primitives or references  are stored in PermGen space    If your static variable is a reference to an object that object itself is stored in the normal sections of the heap  young old generation or survivor space   Those objects  unless they are internal objects like classes etc   are not stored in PermGen space   Example   static int i   1    the value 1 is stored in the PermGen section static Object o   new SomeObject      the reference pointer memory address  is stored in the PermGen section  the object itself is not     A word on garbage collection   Do not rely on finalize   as it s not guaranteed to run  It is totally up to the JVM to decide when to run the garbage collector and what to collect  even if an object is eligible for garbage collection   Of course you can set a static variable to null and thus remove the reference to the object on the heap but that doesn t mean the garbage collector will collect it  even if there are no more references    Additionally finalize   is run only once  so you have to make sure it doesn t throw exceptions or otherwise prevent the object to be collected  If you halt finalization through some exception  finalize   won t be invoked on the same object a second time   A final note  how code  runtime data etc  are stored depends on the JVM which is used  i e  HotSpot might do it differently than JRockit and this might even differ between versions of the same JVM  The above is based on HotSpot for Java 5 and 6  those are basically the same  since at the time of answering I d say that most people used those JVMs  Due to major changes in the memory model as of Java 8  the statements above might not be true for Java 8 HotSpot - and I didn t check the changes of Java 7 HotSpot  so I guess the above is still true for that version  but I m not sure here

User · Answer

static variables are stored in the heap

User · Answer

It is stored in the heap referenced by the class definition  If you think about it  it has nothing to do with stack because there is no scope

User · Answer

Class variables Static variables  are stored as part of the Class object associated with that class  This Class object can only be created by JVM and is stored in permanent generation   Also some have answered that it is stored in non heap area which is called Method Area  Even this answer is not wrong  It is just a debatable topic whether Permgen Area is a part of heap or not  Obviously perceptions differ from person to person  In my opinion we provide heap space and permgen space differently in JVM arguments  So it is a good assumption to treat them differently   Another way to see it  Memory pools are created by JVM memory managers during runtime  Memory pool may belong to either heap or non-heap memory A run time constant pool is a per-class or per-interface run time representation of the constant pool table in a class file  Each runtime constant pool is allocated from the Java virtual machine   s method area and Static Variables are stored in this Method Area  Also this non-heap is nothing but perm gen area Actually Method area is part of perm gen  Reference

User · Answer

When we create a static variable or method it is stored in the special area on heap  PermGen Permanent Generation   where it lays down with all the data applying to classes non-instance data   Starting from Java 8 the PermGen became - Metaspace  The difference is that Metaspace is auto-growing space  while PermGen has a fixed Max size  and this space is shared among all of the instances  Plus the Metaspace is a part of a Native Memory and not JVM Memory  You can look into this for more details

[java] Where are static methods and static variables stored in Java?

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