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JVM - Java Class Load and verification sequence

finding and importing the binary data for a type

1. Verification
ensuring the correctness of the imported type.

step one: Internal Checks : check the structure of the class
step two: Verification of semantic

check other features like : the superclass and final type of object or method

step three: Binary Compatibility
Nother to make sure they are compatible is because Java programs are dynamically linked. Java compilers will often recompile classes that depend on a class you have changed, and in so doing, detect any imcompatibility at complile -time.But there may be times when your complier doesn't recomplile a dependent class. It will also check whether the method is existed or not

step four: Verification of Symbolic References:
Most Java Virtual Machine implementations will likely delay loading classes until they are actually used by the program. When a class file is loaded, it contains symbolic references to other classes and their fields and methods. Dynamic linking is the process of resolving symbolic references into direct references. As the Java Virtual machine executes bytecodes and encounters an opcode that, for the first time, useds a symbolic reference  to another class, the virtual machine must resolve the symbolic reference. The VM performs two basic tasks during resolution:
a. find the class being referenced(loading it if necessary)
b. replace the symbolic reference with a direct reference, such as a pointer or offset, to the class , field, or method

allocating memory for class variables and initializing the memory to default values

invoking Java code that initializes class variables to their proper starting values. 


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