Question

Stack heap questions

5. (16 points) (either 2 or 4 points each, look below for individual section points) Answer some questions about the following Java program; use the line numbers to identify particular state ments or variables. Assume that Widget is a valid class defined in some other file. 1 public class Midi ( 2 public int p, q: // instance variables 3 4 public void funci(int x, int y) ( 5 int p,q 6 7 String S; p=3*25 + x; 9 10 11 public int func20 t 12 p=50; 13 14 Widget w = new Widget(); q = 100; 15 func1 (p.g) w=new Widget(); return 3141; 16 17 18 19 (a) (2 points) Identify a statement where an optimization is likely to occur during the com- pilation process (b) (2 points) Identify an example of a name binding that has a hole in its scope.

Answer 1

a. line no 14 : Widget w = new Widget();

line no 16 : w = new Widget();

both of the statement will be optimized at compilation Time because there is no change in the first object at line no 14

so the compiler will not assign two different object

b. In func1() variable p and q are initialized again hence it will be treated as the local variable of func1 only, the change in these variables will not affect the value of the instance variable.

c. when func2() is calling func1() then there will be new stack allocation for the func1() to store the variable of func1() which will available to only func1() scope.

d. Widget w = new Widget() it will be allocated in the heap

again in line 16 w= new Widget() it will again point to the same heap location.

e. funct1() stack frame will store

p,q,x,y and s along with the instance of the Calling function

f. func2() stack frame will store

w and instance of func1() called function