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 */
} 

public class CommandArgsThree 
{
    public static void main(String [] args) 
    {
        String [][] argCopy = new String[2][2];
        int x;
        argCopy[0] = args;
        x = argCopy[0].length;
        for (int y = 0; y < x; y++) 
        {
            System.out.print(" " + argCopy[0][y]);
        }
    }
}

> java CommandArgsThree 1 2 3

public class TestDogs 
{
    public static void main(String [] args) 
    {
        Dog [][] theDogs = new Dog[3][];
        System.out.println(theDogs[2][0].toString());
    }
}
class Dog { }

public class ExamQuestion6 
{
    static int x; 
    boolean catch()
    {
        x++; 
        return true; 
    } 
    public static void main(String[] args)
    {
        x=0; 
        if ((catch() | catch()) || catch()) 
            x++; 
        System.out.println(x); 
    } 
}

public class If1 
{
    static boolean b;
    public static void main(String [] args) 
    {
        short hand = 42;
        if ( hand < 50 && !b ) /* Line 7 */
            hand++;
        if ( hand > 50 );     /* Line 9 */
        else if ( hand > 40 ) 
        {
            hand += 7;
            hand++;    
        }
        else
            --hand;
        System.out.println(hand);
    }
}

public class Test 
{ 
    public static void main (String args[]) 
    {
        String str = NULL; 
        System.out.println(str); 
    } 
}

System.out.println(Math.sqrt(-4D));

package foo; 
import java.util.Vector; /* Line 2 */
private class MyVector extends Vector 
{
    int i = 1; /* Line 5 */
    public MyVector() 
    { 
        i = 2; 
    } 
} 
public class MyNewVector extends MyVector 
{
    public MyNewVector () 
    { 
        i = 4; /* Line 15 */
    } 
    public static void main (String args []) 
    { 
        MyVector v = new MyNewVector(); /* Line 19 */
    } 
}

TreeSet map = new TreeSet();
map.add("one");
map.add("two");
map.add("three");
map.add("four");
map.add("one");
Iterator it = map.iterator();
while (it.hasNext() ) 
{
    System.out.print( it.next() + " " );
}

1. Assertion checking is typically enabled when a program is deployed.
2. It is never appropriate to write code to handle failure of an assert statement.
3. Assertion checking is typically enabled during program development and testing.
4. Assertion checking can be selectively enabled or disabled on a per-package basis, but not on a per-class basis.
5. Assertion checking can be selectively enabled or disabled on both a per-package basis and a per-class basis.

class s implements Runnable 
{ 
    int x, y; 
    public void run() 
    { 
        for(int i = 0; i < 1000; i++) 
            synchronized(this) 
            { 
                x = 12; 
                y = 12; 
            } 
        System.out.print(x + " " + y + " "); 
    } 
    public static void main(String args[]) 
    { 
        s run = new s(); 
        Thread t1 = new Thread(run); 
        Thread t2 = new Thread(run); 
        t1.start(); 
        t2.start(); 
    } 
}