Java Programming MCQ - Garbage Collection

11. When is the B object, created in line 3, eligible for garbage collection?

  
void start() {
	A a = new A();
	B b = new B();
	a.s(b);
	b = null; /* Line 5 */
	a = null; /* Line 6 */
	System.out.println(""start completed""); /* Line 7 */
}

A. after line 5
B. after line 6
C. after line 7
D. There is no way to be absolutely certain.

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12. How many objects are eligible for garbage collection after execution of line ?

  
public class Test
{
	public static void main(String[] args)
	{
		m1(); // Line
	}
	static void m1()
	{
		Test t1 = new Test();
		Test t2 = new Test();
	}
}

A. 0
B. 1
C. 2
D. 3

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13. After line 11 runs, how many objects are eligible for garbage collection?

  
class X2
{
	public X2 x;
	public static void main(String [] args)
	{
		X2 x2 = new X2(); /* Line 6 */
		X2 x3 = new X2(); /* Line 7 */
		x2.x = x3;
		x3.x = x2;
		x2 = new X2();
		x3 = x2; /* Line 11 */
		doComplexStuff();
	}
}

A. 0
B. 1
C. 2
D. 3

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14. When is the Demo object eligible for garbage collection?

  
class Test
{
	private Demo d;
	void start()
	{
		d = new Demo();
		this.takeDemo(d); /* Line 7 */
	} /* Line 8 */
	void takeDemo(Demo demo)
	{
		demo = null;
		demo = new Demo();
	}
}

A. After line 7
B. After line 8
C. After the start() method completes
D. When the instance running this code is made eligible for garbage collection.

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15. How many objects are eligible for garbage collection after execution of line 8?

  
public class Test
{
	public static void main(String [] args)
	{
		Test t1 = new Test();
		Test t2 = m1(t1); // line 6
		Test t3 = new Test();
		t2 = t3; // line 8
	}
	static Test m1(Test temp)
	{
		temp = new Test();
		return temp;
	}
}

A. 0
B. 1
C. 2
D. 3

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16. When is the Float object, created in line 3, eligible for garbage collection?

  
public Object m()
{
	Object o = new Float(3.14F);
	Object [] oa = new Object[l];
	oa[0] = o; /* Line 5 */
	o = null; /* Line 6 */
	oa[0] = null; /* Line 7 */
	return o; /* Line 8 */
}

A. just after line 5
B. just after line 6
C. just after line 7
D. just after line 8

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