GC

[ushma agarwal]

somebody please tell me what are correct options and why?

  
class A {
  private String name;
  private A otherA;
  public A(String name) {this.name = name;}
  public void other(A otherA) {this.otherA = otherA;}
  public A other() {return otherA;}
  public String toString() {return name;}
  protected void finalize() {System.out.print(name);}
}
class B {
  public static void m1() {
    A a1 = new A("A1"), a2 = new A("A2"), a3 = new A("A3"), a0 = a3;
    a1.other(a2); a2.other(a3); a3.other(a1);
    for(int i = 0; i<4; i++){System.out.print(a0 = a0.other());}
  }
  public static void main(String[] args) {m1(); System.gc();}
}
Which of the following could be a result of attempting to compile and run the program? 
 
a. A1A2A3A1
b. A0A0A0A0A1A2A3
c. A1A2A3A1A2A3
d. A1A2A3A1A1A2A3
e. A1A2A3A1A3A2A1
f. A0A1A2A3A1A2A3
 

thank you in advance!

[Julio Eneriz]

This is the kind of exercise that is much easier to solve with a drawing.

The key is to remember that finalize may be call or not. So we are looking for a beginning of 4 printings with several possible endings (all combinations of 0 or 1 of each A1, A2 and A3).

The beginning of the output is well defined. a0 = a0.other() makes a0 point A1 and returns A1, which toString() method is invoked. Then the same A2, A3 and A1 again.

So every answer with a beginning A1A2A3A1 is valid if the end contains no more than one of A1, A2 or A3 in any order.

Does it make sense?

[Jesper de Jong]

Ushma, please quote your sources.

[Julio Eneriz]

It seems that this topic was also commented here some time ago:

https://coderanch.com/t/246147/java-programmer-SCJP/certification/Garbage-collection

[Jari Timonen]

<offtopic>

The key is to remember that finalize may be call or not.

This is correct(IMHO), but according to Whizlab it isn't. There's some other problems with Whizlab also regarding exceptions. There was two possible answers, but only one was correct (copied code to compiler and tested numerous times. Drag'n'Drop question)
</offtopic>