Topic 10 - Java Memory Management

Question 1

Call stack / runtime stack does what and contains what?

Answer 1

Used for method information while the method is being executed.
Contains:
- formal parameters
- local variables
- return value
- where the method should return to

Question 2

What is Heap used for?

Answer 2

Static information (interfaces and classes). 
Instance information (objects).

Question 3

What happens when an object is created by the New keyword?

Answer 3

1) Reference variable has memory allocated to it in the call stack
2) The object is created using memory in the heap

Question 4

What is being used when a method is being run?

Answer 4

Memory space in the call stack / runtime stack.

Question 5

Explain specifically what happens when a method is used / invoked?

Answer 5

A call frame (activation record) is created and “pushed” onto the runtime stack.

Question 6

What does the Static space in the heap contain?

Answer 6

One copy of the interface and class along with their static variables and methods

Question 7

What does the object space in the heap contain?

Answer 7

1) Value of instance variables

2) Type of object

Question 8

What happens to objects after a method returns?

Answer 8

Object stays on the heap. Even if there is no longer a variable referencing it. Java has automatic garbage collection.