Just after line 5
Just after line 6
Just after line 7 (that is, as the method returns)
Never in this method.
第1题:
1. class Test { 2. private Demo d; 3. void start() { 4. d = new Demo(); 5. this.takeDemo(d); 6. } 7. 8. void takeDemo(Demo demo) { 9. demo = null; 10. demo = new Demo(); 11. } 12. } When is the Demo object, created on line 3, eligible for garbage collection?()
第2题:
12. void start() { 13. A a = new A(); 14. B b = new B(); 15. a.s(b); 16. b = null; 17. a = null; 18. System.out.println(“start completed”); 19. } When is the B object, created in line 14, eligible for garbage collection?()
第3题:
1.public class GC{ 2.private Objec to; 3.private void doSomethingElse(Object obj){o=obj;} 4.public void doSomething(){ 5.Object o=new Object(); 6.doSomethingElse(o); 7.o=new Object(); 8.doSomethingElse(null); 9.o=null; 10.} 11.} When the doSomething method is called,after which line does the Object created in line 5 become available for garbage collection?()
第4题:
public class Test { public static void main(String args[]) { class Foo { public int i = 3; } Object o = (Object)new Foo(); Foo foo = (Foo)o; System.out.println(“i = “ + foo.i); } } What is the result?()
第5题:
public class X { public object m () { object o = new float (3.14F); object oa = new object [1]; oa[0]= o; o = null; oa[0] = null; return o; } } When is the float object created in line 3, eligible for garbage collection?()
第6题:
11. class Snoochy { 12. Boochybooch; 13. public Snoochy() { booch = new Boochy(this); } 14. } 15. 16. class Boochy { 17. Snoochy snooch; 18. public Boochy(Snoochy s) { snooch = s; } 19. } And the statements: 21. public static void main(String[] args) { 22. Snoochy snoog = new Snoochy(); 23. snoog = null; 24. // more code here 25. } Which statement is true about the objects referenced by snoog, snooch, and booch immediately after line 23 executes?()
第7题:
Just after line 13.
Just after line 14.
Never in this method.
Just after line 15 (that is, as the method returns).
第8题:
Line5
Line6
Line7
Line8
Line9
Line10
第9题:
None of these objects are eligible for garbage collection.
Only the object referenced by booch is eligible for garbage collection.
Only the object referenced by snoog is eligible for garbage collection.
Only the object referenced by snooch is eligible for garbage collection.
The objects referenced by snooch and booch are eligible for garbage collection.
第10题:
Line 15 causes a stack overflow.
An exception is thrown at runtime.
The object referenced by a is eligible for garbage collection.
The object referenced by b is eligible for garbage collection.
The object referenced by a is not eligible for garbage collection.
The object referenced by b is not eligible for garbage collection.
第11题:
Just after line 5.
Just after line 6.
Just after line 7.
Just after line 8(that is, as the method returns).
第12题:
After line 16.
After line 17.
After line 18 (when the methods ends).
There is no way to be absolutely certain.
The object is NOT eligible for garbage collection.
第13题:
10. public Object m() { 11. Object o = new Float(3.14F); 12. Object [] oa = new Object[1]; 13. oa[0] = o; 14. o = null; 15. return oa[0]; 16. } When is the Float object, created in line 11, eligible for garbage collection?()
第14题:
1. public class GC { 2. private Object o; 3. private void doSomethingElse(Object obj) { o = obj; } 4. public void doSomething() { 5. Object o = new Object(); 6. doSomethingElse(o); 7. o = new Object(); 8. doSomethingElse(null); 9.o=null; 10. } 11. } When the doSomething method is called, after which line does the Object created in line 5 become available for garbage collection?()
第15题:
1. public class X ( 2. public object m () { 3. object o = new float (3.14F); 4. object [] oa = new object [1]; 5. oa[0]= o; 6. o = null; 7. return oa[0]; 8. } 9. } When is the float object created in line 3, eligible for garbage collection?()
第16题:
1. public class X { 2. public object m () { 3. object o = new float (3.14F); 4. object [] oa = new object [1]; 5. oa[0]= o; 6. o = null; 7. oa[0] = null; 10. return o; 9. } 10. } When is the float object created in line 3, eligible for garbage collection?()
第17题:
1. class Bar { } 1. class Test { 2. Bar doBar() { 3. Bar b = new Bar(); 4. return b; 5. } 6. public static void main (String args[]) { 7. Test t = new Test(); 8. Bar newBar = t.doBar(); 9. System.out.println(“newBar”); 10. newBar = new Bar(); 11. System.out.println(“finishing”); 12. } 13. } At what point is the Bar object, created on line 3, eligible for garbage collection?()
第18题:
Compilation will fail.
Compilation will succeed and the program will print “3”
Compilation will succeed but the program will throw a ClassCastException at line 6.
Compilation will succeed but the program will throw a ClassCastException at line 7.
第19题:
None of these objects are eligible for garbage collection.
Only the object referenced by booch is eligible for garbage collection.
Only the object referenced by snoog is eligible for garbage collection.
Only the object referenced by snooch is eligible for garbage collection.
The objects referenced by snooch and booch are eligible for garbage collection.
第20题:
Line 5
Line 6
Line 7
Line 8
Line 9
Line 10
第21题:
i = 3
Compilation fails.
A ClassCastException is thrown at line 6.
A ClassCastException is thrown at line 7.
第22题:
Just after line 5.
Just after line 6.
Just after line 7.
Just after line 8(that is, as the method returns).
第23题:
Just after line 5
Just after line 6
Just after line 7 (that is, as the method returns)
Never in this method.
第24题:
Just after line 5
Just after line 6
Just after line 7 (that is, as the method returns)
Never in this method.