Vidyavathi saravanan

class Base {} class Agg extends Base{ public String getFields(){ String name = "Agg"; return name; } } public class Avf{ public static void main(String argv[]){ Base a = new Agg(); //Here } } What code placed after the comment //Here will result in calling the getFields method resulting in the output of the string "Agg"? 1) System.out.println(a.getFields()); 2) System.out.println(a.name); 3) System.out.println((Base) a.getFields()); 4) System.out.println( ((Agg) a).getFields());

Answer is 4.
My Question is why not 1 also.
Since methods are called based on Object , why option1 is not correct?

Anyone Please explain

I think again thbs is based on the 'Gauranteed Behavior' . So even if the Objects are made eligible for GC by nulling the reference, only if the GC is scheduled, the memory could be recovered for sure.??!!!

class Red { public int a; public static int b; public static void main (String[] in) { Red r1 = new Red(), r2 = new Red(); r1.a++; r1.b++; System.out.print(r1.a+", "+r1.b+", "+r2.a+", "+r2.b); } } What is the result of attempting to compile and run the program? a. Prints: 0, 0, 0, 0 b. Prints: 0, 1, 1, 1 c. Prints: 1, 1, 1, 0 d. Prints: 1, 1, 0, 1 e. Prints: 1, 1, 0, 0 f. Prints: 1, 1, 1, 1 g. Compile-time error h. Run-time error i. None of the above
Answer is d:

My question is how come the increment statements in static main is able to access the non-static instance variable a. Wont' this generates a compiler-error?

(tag fixed and reformatted)

[ November 14, 2004: Message edited by: Barry Gaunt ]
[ November 14, 2004: Message edited by: Barry Gaunt ]

public class Test1{ public static void main (String args[]) { float f4 = -5.5f; float f5 = 5.5f; float f6 = -5.49f; float f7 = 5.49f; System.out.println("Round f4 is " + Math.round(f4)); System.out.println("Round f5 is " + Math.round(f5)); System.out.println("Round f6 is " + Math.round(f6)); System.out.println("Round f7 is " + Math.round(f7)); } }
Answer is given as -5,6,-5,5.
My doubt is the 3 rd output.
Math.round(-5.49f)--- how come this is -5. As per my understanding it is -6.
Could anyone please explain this. Its confusing me a lot.


Thanks.

11) What is the output (Assuming written inside main) String s1 = new String("amit"); System.out.println(s1.replace('m','r')); System.out.println(s1); String s3="arit"; String s4="arit"; String s2 = s1.replace('m','r'); System.out.println(s2==s3); System.out.println(s3==s4);

Answer is : arit
amit
false
true.
Wont the s2==s3 be true?.
[ November 11, 2004: Message edited by: Barry Gaunt ]

[CODE]
class Trebble{
int i = 99;
}
class Base extends Trebble{
int i =100;
}
public class Central extends Base{
public static void main(String argv[]){
Central c = new Central();
c.wynyard();
}
public void wynyard(){
Trebble t = new Central();
Base b = (Base) t;
System.out.println(b.i);
}

}
[/CODE}
1 Compile time error
2 Compilation and output of 99
3 Compilation and output of 100
4 Compilation, but runtime error because an instance of Trebble cannot be cast to type Base

The Correct Answer is 3).This is on what basis?

Folks,

Is there any way to use 'http://www.jchq.net/phezam/exam.php'( Marcs' Mock) exam to produce only new questions everytime when we freshly take the test. I mean to remember the loginid and to give only the not-so-far-tested(untested) questions.




---Thanks

public class TestQ38 { public static void main (String[] args){ Object obj = buildTest( 3 ) ; System.gc(); System.out.println("exiting"); } public static TestQ38 buildTest(int n ){ TestQ38 t = null ; for( int i = 0 ; i < n ; i++ ){ t = new TestQ38( i ) ; } return t ; } String name ; public TestQ38( int n ){ name = "Number " + n ; } public void finalize(){ System.out.print("finalize " + name ) ; } }
Answer options:
Assume that garbage collection runs and all elligible objects are collected and finalized.
A It does not compile due to incorrect signature of the finalize method.
B It compiles but no text is written when it runs due to incorrect signature of the finalize method.
C Before "exiting" is written, 2 messages from finalize will be printed.
D Before "exiting" is written, 3 messages from finalize will be printed

Which one would be the answer?
(code tag fixed and missing }s added )
[ November 09, 2004: Message edited by: Barry Gaunt ]

This is one of the Mock Questions.

1. A constructor may not be declared as private
2 A Constructor with no arguments will be the default constructor
3 Constructors cannot be overloaded
4 A call to a constructor in a parent class can only be made from within a constructor


The correct answer : 4. Iam not able to understand what the 4th statement means. Anyone please explain this?

-Thanks

There is a question in one of Marc exam. Sorry I dont remember the exact wordings. But the essence is -
Is 'synchronized' keyword to be used only within classes that extend Thread?

All Test Takers,

Would u please suggest me as where to start with these Mock Tests? What are the different types available? Are u referring to the Ranch's compilation of mock tests or some other mock tests.

Appreciate ur reply.


--Vidya

Mark,

Please let me know if u have any of ur tests orgainsed objectivewise?


Thanks!!!

I have a doubt.

The String Objects are created in ' String pool'. (ma,ba,co,de).
Whether they are eligible for GC.? Or they are neglected by GC?

This is one of the questions from K&B.

Assume u have a class that holds two private variables: 'a' and 'b'. Which of the following pairs can prevent concurrent access problems in that class.?

A. public int read ( int a, int b) { return a+b :wink: public void set (int a , int b){ this.a=a;this.b=b;} B. public synchronized int read (int a, int b){ return a+b;} public synchronized void set(int a , int b){this.a =a;this.b=b;} C. public int read( int a, int b){ synchronize(a){ return a+b;}} public void set (int a, int b){ synchronized (a){ this.a=a; this.b=b;}} D. public int read(int a, intb ){ synchronized(a){ return a+b;} public void set (int a, int b){ synchronized(b)( this.a =a;this.b=b;}} E. public synchronized(this) int read(int a, int b){ return a+b :wink: public synchronized (this ) void set(int a , int b){this.a =a;this.b=b;} F. public int read( int a, int b){ synchronize(this){ return a+b;}} public void set (int a, int b){ synchronized (this){ this.a=a; this.b=b;}}

Answers: B and F
My question is why not E ?

class A extends Thread { private Object obj; public A(Object obj) {this.obj = obj;} public void run() { try { synchronized (obj) {obj.wait();} } catch (InterruptedException ie) {} System.out.print(Thread.currentThread().getName()); }} class B { private void m1() { for (int i = 0; i < 10; i++) { A t1 = new A(this); t1.setName(String.valueOf(i)); t1.setDaemon(true); t1.start(); } synchronized (this) {notifyAll();} } public static void main(String[] args) {new B().m1();} } What are the possible results of attempting to compile and run the program? a. All of the numbers 0 through 9 must always be printed b. Some or all of the numbers 0 through 9 could be printed c. Nothing is printed d. Run-time error

Answers: b,c
Could anyone explain how the answer is. I could guess b. But how come c?
Appreciate ur time and response!