Java quiz questions

What will be the output of the program?

public class X 
{  
    public static void main(String [] args) 
    {
        try 
        {
            badMethod();  
            System.out.print("A");  
        } 
        catch (RuntimeException ex) /* Line 10 */
        { 
            System.out.print("B"); 
        } 
        catch (Exception ex1) 
        { 
            System.out.print("C"); 
        } 
        finally 
        {
            System.out.print("D"); 
        } 
        System.out.print("E"); 
    } 
    public static void badMethod() 
    { 
        throw new RuntimeException(); 
    } 
}

1. BD

2. BCD

3. BDE

4. BCDE

What will be the output of the program?

int x = 3; 
int y = 1; 
if (x = y) /* Line 3 */
{
    System.out.println("x =" + x); 
}

1. x = 1

2. x = 3

3. Compilation fails.

4. The code runs with no output.

What will be the output of the program?

for (int i = 0; i < 4; i += 2) 
{ 
    System.out.print(i + " "); 
} 
System.out.println(i); /* Line 5 */

1. 0 2 4

2. 0 2 4 5

3. 0 1 2 3 4

4. Compilation fails.

What will be the output of the program?

int x = l, y = 6; 
while (y--) 
{
    x++; 
} 
System.out.println("x = " + x +" y = " + y);

1. x = 6 y = 0

2. x = 7 y = 0

3. x = 6 y = -1

4. Compilation fails.

What will be the output of the program?

class SSBool 
{
    public static void main(String [] args) 
    {
        boolean b1 = true;
        boolean b2 = false;
        boolean b3 = true;
        if ( b1 & b2 | b2 & b3 | b2 ) /* Line 8 */
            System.out.print("ok ");
        if ( b1 & b2 | b2 & b3 | b2 | b1 ) /*Line 10*/
            System.out.println("dokey");
    }
}

1. ok

2. dokey

3. ok dokey

4. No output is produced

5. Compilation error

What will be the output of the program?

class Bitwise 
{
    public static void main(String [] args) 
    {
        int x = 11 & 9;
        int y = x ^ 3;
        System.out.println( y | 12 );
    }
}

1. 0

2. 7

3. 8

4. 14

What will be the output of the program?

class Equals 
{
    public static void main(String [] args) 
    {
        int x = 100;
        double y = 100.1;
        boolean b = (x = y); /* Line 7 */
        System.out.println(b);
    }
}

1. true

2. false

3. Compilation fails

4. An exception is thrown at runtime

What will be the output of the program?

class PassA 
{
    public static void main(String [] args) 
    {
        PassA p = new PassA();
        p.start();
    }
    void start() 
    {
        long [] a1 = {3,4,5};
        long [] a2 = fix(a1);
        System.out.print(a1[0] + a1[1] + a1[2] + " ");
        System.out.println(a2[0] + a2[1] + a2[2]);
    }
    long [] fix(long [] a3) 
    {
        a3[1] = 7;
        return a3;
    }
}

1. 12 15

2. 15 15

3. 3 4 5 3 7 5

4. 3 7 5 3 7 5

What will be the output of the program?

public class Test 
{
    public int aMethod()
    {
        static int i = 0;
        i++;
        return i;
    }
    public static void main(String args[])
    {
        Test test = new Test();
        test.aMethod();
        int j = test.aMethod();
        System.out.println(j);
    }
}

1. 0

2. 1

3. 2

4. Compilation fails.

Which statement is true given the following?

Double d = Math.random();

1. 0.0 < d <= 1.0

2. 0.0 <= d < 1.0

3. Compilation fail

4. Cannot say.

What will be the output of the program?

public class Test 
{ 
    public static void main(String[] args) 
    {
        final StringBuffer a = new StringBuffer(); 
        final StringBuffer b = new StringBuffer(); 
        new Thread() 
        { 
            public void run() 
            {
                System.out.print(a.append("A")); 
                synchronized(b) 
                { 
                    System.out.print(b.append("B")); 
                } 
            } 
        }.start(); 
        new Thread() 
        {
            public void run() 
            {
                System.out.print(b.append("C")); 
                synchronized(a) 
                {
                    System.out.print(a.append("D")); 
                } 
            } 
        }.start(); 
    } 
}

1. ACCBAD

2. ABBCAD

3. CDDACB

4. Indeterminate output

What will be the output of the program?

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

1. -2

2. NaN

3. Compile Error

4. Runtime Exception

What will be the output of the program?

String x = new String("xyz");
String y = "abc";
x = x + y;

How many String objects have been created?

1. 2

2. 3

3. 4

4. 5

Which of the following would compile without error?

1. int a = Math.abs(-5);

2. int b = Math.abs(5.0);

3. int c = Math.abs(5.5F);

4. int d = Math.abs(5L);

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();
    }
}

1. 0

2. 1

3. 2

4. 3

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 */
}

1. after line 5

2. after line 6

3. after line 7

4. There is no way to be absolutely certain.

which of these will create and start this thread?

public class MyRunnable implements Runnable 
{
    public void run() 
    {
        // some code here
    }
}

1. new Runnable(MyRunnable).start();

2. new Thread(MyRunnable).run();

3. new Thread(new MyRunnable()).start();

4. new MyRunnable().start();

Which method registers a thread in a thread scheduler?

1. run();

2. construct();

3. start();

4. register();

Which cannot directly cause a thread to stop executing?

1. Calling the SetPriority() method on a Thread object.

2. Calling the wait() method on an object.

3. Calling notify() method on an object.

4. Calling read() method on an InputStream object.

Which three are methods of the Object class?

1. notify();
2. notifyAll();
3. isInterrupted();
4. synchronized();
5. interrupt();
6. wait(long msecs);
7. sleep(long msecs);
8. yield();

1. 1, 2, 4

2. 2, 4, 5

3. 1, 2, 6

4. 2, 3, 4