In this lecture we are discussing:
1) Memory management in java and typed of categories to store data in memory.
2)What is stack ?
3)What is heap ?
4) where instance variable and local variable is allocated?
#1
In java we are managing our managing our memory using two data structure stack and heap.
two categories to store data in memory:
1) Stack data structure
2) heap data structure
#2
Stack is data structure which follow LIFO(Last in First Out) principle.
#3
heap is data structure which is used to store data in form of object and object is a collection of data and method.
#4
class Student{
int instVariable; //store in object and object created in heap
public static void main(String []args){
int localVariable=0; //local variable store in stack frame of method in stack area.
Student st=new Student(); //st is reference variable store address of new Student() object
}
public int add(int num1,int num2){
return num1+num2;
}
}
— instance variable stored in object and object are in heap therefore we can say that instance variable created in heap.
— method declaration and definition is present in object but actual implementation present in stack frame of stack.
— local variable created in stack during call of method.
— stack frame of called method is present in stack area.
— st is reference variable created inside the current stack frame and it is reference variable store address of student object created in heap area.
— new Student() create object in heap area and pointed by his reference variable.