jvm如何运行程序

Question

program 1: when i write one simple class B without creating object in my java program. how JVM allocates memory to class code which contain member fields and member function.

class B
{
     int a=10;
     public void print()
     {
         System.out.println("inside B class");
     }

}

program 2:And when i create the object of that class then how jvm allocate memory for object...see code below

class B
{
    int a=10;
    public void print()
    {
        System.out.println("inside B class");
    }

    public static void main(String args[])
    {
        B b=new B();
        b.print();

    }
}

Answer 1

There are three levels of allocation in this example:

• when the class is loaded (usually the first time it is referenced somewhere in your code), then memory for its structure, its code and it static fields is allocated.

• when an instance is created ( new B() ) then memory for the non-static fields and some metadata (object header) is allocated. This memory is on the heap.

• when a method is called, then memory from the stack is allocated for local variables inside that method.

Answer 2

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