OCPJP 6 Mock Exam

1 . Consider the following line of code:

public class Test{
   public void main(){
   System.out.println(&quot;Hi&quot;);
}
public static void main (String [] args)
{
Test t=new Test();
t.main();
}
}

What will be happen if you compile and run above code?

It will not compile
It will not run
It will compile but will not run
It will output “Hi”

2 . After execution of the code fragment below, what are the value of the variables x1, y1, and z1?

int x=10; int y =10; int z=10; int x1, y1, z1;
x1=++y;
y1=z++;
z1=z;

Choose the one below:

x1 = 10 , y1 = 10 and z1=10
x1 = 10, y1 = 11, and z1=10
x1=10, y1 = 10, and z1=11
x1=11, y1=10, and z1=11

3 . What will be the output?

Class Test{
public int addTest(int x, int y)
{
      x=x+1; y=y+1;
      int z=(x+y);
      return z;
}
public static void main(String [] args)
{
      int x=10; int y=10; int z=0;
      Test t=new Test();
      z= t.addTest(x,y);
      System.out.println(&quot;x=&quot;+x+&quot;, y=&quot;+y+&quot;, z=&quot;+z);
}
}

Choose the one below:

x=10, y=10, z=22
x=11, y=11, z=22
x=10, y=10, z=20
x=11, y=11, z=20

4 . What will be the output of the program.?
Assume that MyList class is declared in MyList.java
and ListManager class is declared in ListManager.java file.

public class MyList{
int size=1;
public static void main(String [] args)
{
      MyList list=new MyList();
     list.size=10;
     ListManager lm=new ListManager();
     lm.expandList(list);
    System.out.println(&quot;list.size=&quot;+list.size);
}
}  //end of MyList
public class ListManager{
public void expandList(MyList l)
{
     l.size=l.size+10;
}
}//end of ListManager

Choose the one below:

list.size=0
list.size=10
list.size=11
list.size=20

5 . If int x = -1 then which of the following expression results in a positive value in x?

x=x>>>32
x=x>>>5
x=x>>5
x=~x

6 . Which of the following lines of code would print “Equal” when you run it?

int x=1; float y=1.0F; if(x==y){ System.out.println(“Equal”);}
int x=1; Integer y= new Integer(1); if(x==y) { System.out.println(“Equal”);}
Integer x=new Integer(1); Integer y=new Intger(1); if(x==y){ System.out.println(“Equal”);}
String x=”1″; String y=”1″; if (x==y) { System.out.println(“Equal”);}

7 . Which of the following declarations are correct for the top level class?

public synchronized class MyTest extends Thread
private class MyTest extends Thread
public abstract class MyTest extends Thread
class MyTest extends Thread

8 . Consider the following lines of code:

class Test{
String x;
public void testDemo(int n)
{
       String y;
       if ( n&gt;0) {
              y=&quot;Hello&quot;;
       }
       System.out.println(x+y);
}
public static void main(String [] args)
{
          Test test=new Test();
          test.testDemo(2);
}
}

What will happen if you try to compile and run above code?

It will produce compiler warning that variable y may not have been initialized
It will produce compiler warning that variable x may not have been initialized
It will output “Hello”
It will output “nullHello”

9 . Consider that Parent and Child classes are defined in two different files as below:

class Parent{
public Parent(){
System.out.println(&quot;I am Parent&quot;);
}
}
class Child extends Parent{
public Child(int x){
System.out.println(&quot;I am Child&quot;);
}
public static void main(String [] args){
Child c=new Child(10);
}
}

What will be output if you try to compile and run above code?

It will not compile.
It will compile successfully. It will output “I am Parent” and then “I am Child.”
It will compile successfully. It will output “I am Child” and then “I am Parent.”
It will compile successfully, but will not run.

10 . Consider following code:

public class MyList{
static int size;
public expandList(int newSize){
ListExpander lexp=new ListExpander();
Vector expandedList=lexp.expand();
     class ListExpander{
     public Vector expand(){
        Vector v=new Vector(this.size+newSize);
        return v;
     }
     }
}
}

What will happen if you attempt to compile above code?

compiler error, “cannot refer inside an inner class to a static variable.”
compiler error, “cannot refer inside an inner class to to a non-final variable newSize defined in a different method.”
Both of the above
None of the above

11 . Consider following code:

public class Parent{
public  int size =0;
static class InnerClass{
public void incrementParentSize(){
    XXX=XXX+10;
}
}
}

In above code, how can you access ‘size’ variable (of outer class Parent) inside innerclass at the place of ‘XXX’ ?

super.size
this.size
Parent.size
Can not access it

12 . Assume that Parent and Child classes are in different files:

public class Parent{
public Parent(int x, int y)
{
       System.out.println(&quot;Created Parent&quot;);
}
}//end of Parent class
public class Child extends Parent{
public Child(int x, int y){
//
}
public Child(int x, int y, int z){
System.out.println(&quot;Creating child&quot;);
this(x,y);
}
public static void main(String [] args){
Child c=new Child(1,2,3);
}
}

What will happen if you try to compile and run above program?

It will compile successfully. It will output “Created Parent” and then “Creating child”
It will compile successfully. It will output “Creating child” and then “Created Parent”
It will not compile giving warning, “Explicit constructor invocation must be first statement in constructor.”
It will not compile giving warning, “Expression is not a valid block statement.”

13 . Consider following code:

public class OuterClass{
class InnerClass{
}
public void innerClassDemo(){
//Explicit instance of InnerClass
}
}

In above code, how can you explicitly create an instance of InnerClass?

InnerClass i=InnerClass();
InnerClass i=OuterClass.InnerClass();
InnerClass i=new OuterClass ().new InnerClass();
OuterClass.InnerClass i=new OuterClass.InnerClass();

14 . Please select valid array declaration(s):

int x[20];
int []x=new int[20];
int [][] x=new int [20][];
int [][][] x=new int[20][20][20];
int [] x={1,2,3};

15 . Consider following code:

public class Test{
protected void demo() throws NumberFormatException, ArrayIndexOutOfBoundsException {
//something here
}
public void demo(String s){
//something here
}
}//end of Test class

Please select true statement(s) for demo code?

It is an example of overloading method
It is an example of overriding method
Both of the above
None of the above

16 . For the following code, please consider that super class is defined in question #15:

public class MyTest extends Test{
private void demo() throws IndexOutOfBoundsException, ClassNotFoundException
{
//something here
}
}//end of MyTest class

What will happen if you try to compile above code ?

It will compile successfully.
Compiler error: Exception java.lang.ClassNotFoundException in throws clause of void MyTest.demo() is not compatible with void Test.demo().
Compiler error: Cannot reduce visibility of the inherited method from Test.
Both B and C

17 . Consider the following code:

public class Test{
public void demo(String [] list){
try{
         String s=list[list.length+1];
        System.out.println(s);
    }catch(ArrayIndexOutOfBoundException e){
   return;
  }finally{
      System.out.println(&quot;Finally here.&quot;);
}
public static void main(String [] args){
Test t=new Test();
String [] list={&quot;one&quot;,&quot;two&quot;};
t.demo(list);
System.out.println(&quot;Done!&quot;);
}
}//end of Test class

What happen if you try compile and run above code ?

It will not compile.
It will output “null” and then “Finally here.”
It will output “Done!”
It will output “Finally here” and then “Done!”

18 . Please consider following code:

public class Test{
public static void demo(String s)
{
      debug(&quot;In demo:&quot;+s);
}
private void debug(String s){
System.out.println(s);
}
public static void main(String [] args){
Test.demo(&quot;Hello&quot;);
}
}

What will happen if you try to compile and run above code ?

It will compile successfully, but will not run.
It will compile successfully, and outputs “In demo:Hello.”
It will not compile with error message “Can not make a static reference to the instance method named.”
None of the above

19 . Consider the following code:

/** File Drawable.java */
public interface Drawable{
public void draw();
public void  fill();
} /** End of file Drawable.java*/

/** File Circle.java */
public class Circle implements Drawable{
int center=0;
public void draw(){
System.out.println(&quot;Drawing circle&quot;);
}
public static void main(String [] args){
Circle c=new Circle();
c.draw();
}
} /** End of file Circle.java */

If you attempt to compile and run Circle class what will be output?

It will compile successfully, and outputs “Drawing circle.”
It will not compile, and reports error: “class Circle must implement inherited abstract method void Drawable.fill.”
It will not compile, and reports error: “Method Drawable.fill requires a body instead of a semicolon.”
None of the above

20 . What will be the output?

int x=2; int y=3; int z=4;
if(x&gt;2){
    System.out.println(&quot;Tested x&quot;);
}if(y&lt;3){
   System.out.println(&quot;Tested y&quot;);
}if (z&lt;=3){
   System.out.println(&quot;Tested z&quot;);
}

Choose the one below:

Tested x.
Tested y.
Tested z.
None of the above.

21 . Consider the following code:

for( int i=0;i&lt;2;i++)
{
      for(int j=i;j&lt;3; j++)
     {
             if (i==j)
             {
                   continue;
             }
             System.out.println(&quot;i=&quot;+i+&quot; j=&quot;+j);
     }
}