Which two statements are true about comparing two instances of the same class, given that the equals() and hashCode() methods have been properly overridden?

1. If the equals() method returns true, the hashCode() comparison == must return true.
2. If the equals() method returns false, the hashCode() comparison != must return true.
3. If the hashCode() comparison == returns true, the equals() method must return true.
4. If the hashCode() comparison == returns true, the equals() method might return true.

boolean bool = true; 
if(bool = false) /* Line 2 */
{
    System.out.println("a"); 
} 
else if(bool) /* Line 6 */
{
    System.out.println("b"); 
} 
else if(!bool) /* Line 10 */
{
    System.out.println("c"); /* Line 12 */
} 
else 
{
    System.out.println("d"); 
}

class s1 extends Thread
{ 
    public void run() 
    { 
        for(int i = 0; i < 3; i++) 
        { 
            System.out.println("A"); 
            System.out.println("B"); 
        } 
    } 
} 
class Test120 extends Thread 
{ 
    public void run() 
    { 
        for(int i = 0; i < 3; i++) 
        { 
            System.out.println("C"); 
            System.out.println("D"); 
        } 
    } 
    public static void main(String args[]) 
        { 
        s1 t1 = new s1(); 
        Test120 t2 = new Test120(); 
        t1.start(); 
        t2.start(); 
    } 
}

class Exc0 extends Exception { } 
class Exc1 extends Exc0 { } /* Line 2 */
public class Test 
{  
    public static void main(String args[]) 
    { 
        try 
        {  
            throw new Exc1(); /* Line 9 */
        } 
        catch (Exc0 e0) /* Line 11 */
        {
            System.out.println("Ex0 caught"); 
        } 
        catch (Exception e) 
        {
            System.out.println("exception caught");  
        } 
    } 
}

class Test 
{
    public static void main(String [] args) 
    {
        int x= 0;
        int y= 0;
        for (int z = 0; z < 5; z++) 
        {
            if (( ++x > 2 ) && (++y > 2)) 
            {
                x++;
            }
        }
        System.out.println(x + " " + y);
    }
}

1. The Iterator interface declares only three methods: hasNext, next and remove.
2. The ListIterator interface extends both the List and Iterator interfaces.
3. The ListIterator interface provides forward and backward iteration capabilities.
4. The ListIterator interface provides the ability to modify the List during iteration.
5. The ListIterator interface provides the ability to determine its position in the List.

public class Test 
{ 
    public static void main (String[] args) 
    {
        String foo = args[1]; 
        String bar = args[2]; 
        String baz = args[3]; 
        System.out.println("baz = " + baz); /* Line 8 */
    } 
}

> java Test red green blue

public class Foo 
{  
    public static void main(String[] args) 
    {
        try 
        { 
            return; 
        } 
        finally 
        {
            System.out.println( "Finally" ); 
        } 
    } 
}

public class Test138 
{ 
    public static void stringReplace (String text) 
    {
        text = text.replace ('j' , 'c'); /* Line 5 */
    } 
    public static void bufferReplace (StringBuffer text) 
    { 
        text = text.append ("c");  /* Line 9 */
    } 
    public static void main (String args[]) 
    { 
        String textString = new String ("java"); 
        StringBuffer textBuffer = new StringBuffer ("java"); /* Line 14 */
        stringReplace(textString); 
        bufferReplace(textBuffer); 
        System.out.println (textString + textBuffer); 
    } 
}

public class WrapTest 
{
    public static void main(String [] args) 
    {
        int result = 0;
        short s = 42;
        Long x = new Long("42");
        Long y = new Long(42);
        Short z = new Short("42");
        Short x2 = new Short(s);
        Integer y2 = new Integer("42");
        Integer z2 = new Integer(42);

        if (x == y) /* Line 13 */
            result = 1;
        if (x.equals(y) ) /* Line 15 */
            result = result + 10;
        if (x.equals(z) ) /* Line 17 */
            result = result + 100;
        if (x.equals(x2) ) /* Line 19 */
            result = result + 1000;
        if (x.equals(z2) ) /* Line 21 */
            result = result + 10000;

        System.out.println("result = " + result);
    }
}