Static Vs Transient

Static variables cannot be serialized since the static variables are variable per Class but serialization is intended to serialize the class instance.but still...............
Static variables can be made to serialize if values are assigned there at time of initialization itself as below.
Class Employee implements Serializable{
static String name;
Employee(){
}

Employee(String name){
this.name = name;// initialized at objet creation....... saved suring serialzation
}

}

Class Client{
public static void main(String args[]){

  Employee e = new Employee();
 e.name="Akkhil"; // a varianble named per class hence cannot serialized

Employee e2 = new Employee("akkhil");
}

}

Garbage Collection: Java

Garbage Collection:
Has following steps:
1.Marking: Marking live and dead Objects.
2.Normal deletion and Compact Deletion
  Since many Objects live for shorter time;
 thus, Generational GC
 Young: called minor collection
 Old:called major collection, objects move to Old geneartion for young geneartion after a threshold time elapses.
 Permanent:Conatins meta dta needed for classes from JVM or libraries gets collected under full garbage collection

When Objects are created they are moved to EDEN space, one first MINOR GC moves to survival space1.Same is repeated for second MINOR GC and the objects that survives are promoted from
YOUNG generation to OLD , after they crosses the age threshold.

ConcurrentMarkSweep is the collector in latest java, here garbage collection is done without moving the live Objects

java Basics

JAVA is an architecture neutral language. As stated in article1, the JAVA compiler generates JAVA Virtual Machine codes instead of machine codes specific to the computer system we are using.  

These Virtual Machine codes, or JAVA bytecodes, are all architecturally neutral; the compiled codes are executable on any processors and systems, provided of course, that the JAVA Virtual machine (interpreter) is installed in those systems

JVM Architecture:
ClassLoader:RunTime Data Area: Aresa used during runtime which comprsises of some data Areas relative to JVM and Thread LifeCycle span.
PC Register: Contains address of the JVM instrauction if NOT native, i.e. method written in C or that doenot run in JVM.
JVM Stack: Fixed or dynamic Sized Stack containg frames,i..e local variables or partial results and is created at time of Thread creation.
This might lead to two errors:
If thread execution needs larger stack for execution than throws stackOverFlow error and if stack allocation is dynamic,the
Stack might get allocated extra memory but still the Stack memory required by JVM for new Thread might run out of memory thus causing OutOFMemory Error.
Heap: Runtime area ffrom which memory is allocated to all class instances and arrays.
Method Area: Comprisies within heap and is shared among all threads of JVM and conaytins per class structures as:
constant pool,field, methods, data, Interfaces.This contains the compiled code.
This method area further comprises of: run-time contant pool: this is the per-class,per-interface runtime representation of the class anf it contains the literals or symbolic references generated by compiler. and is created the time class or interface is created.
Native Method Stacks:To Supports native methods.
Frames: used to store data and partial results, return vales from method.
Heap
^
Method Area
^
Constant Pool

JVM has following lifecycle for classes:
Loading: Finding the binary representation for the class/interface with particular name and create class/interface from that binary represenatation.
Linking:Combinting class/interfcae with run time state of JVM so can be executed.
Initializing:intiialzation of classes

JVM StartUp:
The Java Virtual Machine starts up by creating an initial class, which is specified in an implementation-dependent manner, using the bootstrap class loader (§5.3.1). The Java Virtual Machine then links the initial class, initializes it, and invokes the public class method void main(String[]). 
JVM implemention as: Linux based, windows. JRE is implementaion for JVM

Loading
^
Linking
^
Initializing
^
Vertfication, check if class/interfcae are structurally correct

To Exit JVM:Runtime class exit method

JIT: Just in Time compiler is part of JVm and it bypasses the interpretaion phase by compiling bytecodea to machine native language at runtime