64 Java questions for any job interview

1. Which

of the following are valid definitions of an application’s main( ) method?

a) public static void main();

b) public static void main( String args );

c) public static void main( String args[] );

d) public static void main( Graphics g );

e) public static boolean main( String args[] );

2. If MyProg.java were compiled as an

application and then run from the command line as:

              java MyProg I like tests

what would be the value of args[ 1 ] inside

the main( ) method?

a) MyProg

b) "I"

c) "like"

d) 3

e) 4

f) null until a value is assigned



3. Which of the following are Java keywords?

a) array

b) boolean

c) Integer

d) protect

e) super

4. After the declaration:

char[] c = new char[100];

what is the value of c[50]?

a) 50

b) 49

c) ‘\u0000′

d) ‘\u0020′

e) " "

f) cannot be determined

g) always null until a value is

assigned

5. After the declaration:

int x;

the range of x is:

a) -2³¹ to 2³¹-1



b) -2¹⁶ to 2¹⁶ -

1

c) -2³² to 2³²

d) -2¹⁶ to 2¹⁶

e) cannot be determined; it depends on

the machine

6. Which identifiers are valid?

a) _xpoints

b) r2d2

c) bBb$

d) set-flow

e) thisisCrazy

7. Represent the number 6 as a hexadecimal

literal.



8. Which of the following statements assigns "Hello Java" to the

String variable s?

a) String s = "Hello Java";

b) String s[] = "Hello Java";

c) new String s = "Hello Java";

d) String s = new String("Hello Java");

9. An integer, x has a binary value (using 1

byte) of 10011100. What is the binary value of z after these statements:

int y = 1 <<>

int z = x & y;

a) 1000 0001

b) 1000 0000

c) 0000 0001

d) 1001 1101

e) 1001 1100

10. Which statements are accurate:

a) >>

performs signed shift while >>> performs an unsigned shift.

b) >>> performs a

signed shift while >> performs an unsigned shift.

c) << performs a

signed shift while <<< performs an insigned shift.

d) <<< performs a

signed shift while << performs an unsigned shift.

11. The statement …

String s = "Hello" +

"Java";

yields the same value for s as …

String s = "Hello";

String s2= "Java";

s.concat( s2 );

True

False

12. If you compile and execute an application

with the following code in its main() method:

        String s = new String( "Computer" );

        if( s == "Computer" )

               System.out.println( "Equal A" );

        if( s.equals( "Computer" ) )

               System.out.println( "Equal B" );

a) It will not compile because the

String class does not support the = = operator.

b) It will compile and run, but

nothing is printed.

c) "Equal A" is the only

thing that is printed.

d) "Equal B" is the only

thing that is printed.

e) Both "Equal A" and

"Equal B" are printed.

13. Consider the two statements:

        1. boolean passingScore = false && grade == 70;

        2. boolean passingScore = false & grade == 70;

The expression

grade == 70

is evaluated:

a) in both 1 and 2

b) in neither 1 nor 2

c) in 1 but not 2

d) in 2 but not 1

e) invalid because false should be

FALSE

14. Given the variable declarations below:

byte myByte;

int myInt;

long myLong;

char myChar;

float myFloat;

double myDouble;

Which one of the following assignments would

need an explicit cast?

a) myInt

= myByte;

b) myInt

= myLong;

c) myByte

= 3;

d) myInt

= myChar;

e) myFloat

= myDouble;

f) myFloat

= 3;

g) myDouble

= 3.0;

15. Consider this class example:

class MyPoint 

{  void myMethod() 

   {  int x, y;

      x = 5; y = 3;

      System.out.print( " ( " + x + ", " + y + " ) " );

      switchCoords( x, y );

      System.out.print( " ( " + x + ", " + y + " ) " );

   }

   void switchCoords( int x, int y ) 

   {  int temp;

      temp = x;

      x = y;

      y = temp;

      System.out.print( " ( " + x + ", " + y + " ) " );

   }

}

What is printed to standard output if myMethod()

is executed?

a) (5, 3) (5, 3) (5, 3)

b) (5, 3) (3, 5) (3, 5)

c) (5, 3) (3, 5) (5, 3)

16. To declare an array of 31 floating

point numbers representing snowfall for each day of March in Gnome, Alaska,

which declarations would be valid?

a) double

snow[] = new double[31];

b) double

snow[31] = new array[31];

c) double

snow[31] = new array;

d) double[]

snow = new double[31];

17. If arr[] contains only positive integer values, what does this

function do?

public int guessWhat( int arr[] )

{  int x= 0;

   for( int i = 0; i <>

      x = x <>

   return x;

}

a) Returns the index of the highest

element in the array

b) Returns true/false if there

are any elements that repeat in the array

c) Returns how many even numbers are

in the array

d) Returns the highest element in the

array

e) Returns the number of question

marks in the array

18. Consider the code below:

arr[0] = new int[4];

arr[1] = new int[3];

arr[2] = new int[2];

arr[3] = new int[1];

for( int n = 0; n <>

System.out.println( /* what goes here? */ );

Which statement below, when inserted as the

body of the for loop, would print the number of values in each row?

a) arr[n].length();

b) arr.size;

c) arr.size-1;

d) arr[n][size];

e) arr[n].length;

19. If size = 4, triArraylooks like:

int[][] makeArray( int size) 

{  int[][] triArray = new int[size] [];

   int val=1;

   for( int i = 0; i <>

   {  triArray[i] = new int[i+1];

          for( int j=0; j <>

      {  triArray[i][j] = val++;

      }

   }

   return triArray;

}

a)

1 2 3 4

5 6 7

8 9

10

b)

1 4 9 16

c)

1 2 3 4

d)

1 2 3 4

5 6 7 8

9 10 11 12

13 14 15 16

e)

1

2 3

4 5 6

7 8 9 10

20. Which of the following are legal

declarations of a two-dimensional array of integers?

a) int[5][5]a = new int[][];

b) int a = new int[5,5];

c) int[]a[] = new int[5][5];

d) int[][]a = new[5]int[5];

21. Which of the following are correct methods

for initializing the array "dayhigh" with 7 values?

a) int dayhigh = { 24, 23, 24, 25, 25, 23, 21 };

b) int dayhigh[] = { 24, 23, 24, 25, 25, 23, 21 };

c) int[] dayhigh = { 24, 23, 24, 25, 25, 23, 21 };

d) int dayhigh [] = new int[24, 23, 24, 25, 25, 23, 21];

e) int dayhigh = new[24, 23, 24, 25, 25, 23, 21];

22. If you want subclasses to access, but not to

override a superclass member method, what keyword should precede the name of

the superclass method?



23. If you want a member variable to not be accessible outside the current

class at all, what keyword should precede the name of the variable when

declaring it?



24. Consider the code below:

public static void main( String args[] )

{  int a = 5;

   System.out.println( cube( a ) );

}

int cube( int theNum )

{

   return theNum * theNum * theNum;

}

What will happen when you attempt to compile and run this code?

a) It will not compile because cube is

already defined in the java.lang.Math class.

b) It will not compile because cube is

not static.

c) It will compile, but throw an

arithmetic exception.

d) It will run perfectly and print

"125" to standard output.

25. Given the variables defined below:

int one = 1;

int two = 2;

char initial = ‘2′;

boolean flag = true;

Which of the following are valid?

a) if(

one ){}

b) if(

one = two ){}

c) if(

one == two ){}

d) if(

flag ){}

e) switch(

one ){}

f) switch(

flag ){}

g) switch(

initial ){}

26. If val = 1 in the code below:

switch( val ) 

{  case 1: System.out.print( "P" );

   case 2: 

   case 3: System.out.print( "Q" );

      break;

   case 4: System.out.print( "R" );

   default: System.out.print( "S" );

}

Which values would be printed?

a) P

b) Q

c) R

d) S

27. Assume that val has been defined as an int for the

code below:

if( val > 4 ) 

{  System.out.println( "Test A" );

}

else if( val > 9 ) 

{  System.out.println( "Test B" );

}

else System.out.println( "Test C" );

Which values of val will

result in "Test C" being printed:

a) val < 0

b) val between 0 and 4

c) val between 4 and 9

d) val > 9

e) val = 0

f) no values for val will be satisfactory

28. What exception might a wait()

method throw?



29. For the code:

m = 0;

while( m++ <>

   System.out.println( m );

Which of the following are printed to

standard output?

a) 0

b) 1

c) 2

d) 3

e) Nothing and an exception

is thrown

30. Consider the code fragment below:

outer: for( int i = 1; i <3;>

   {  inner: for( j = 1; j <>

      {  if( j==2 )

            continue outer;

            System.out.println( "i = " +i ", j = " + j );

      }

   }    

Which of the following would be printed to standard output?

a) i = 1, j = 1

b) i = 1, j = 2

c) i = 1, j = 3

d) i = 2, j = 1

e) i = 2, j = 2

f) i = 2, j = 3

g) i = 3, j = 1

h) i = 3, j = 2

31. Consider the code below:

void myMethod() 

{  try 

   {  

      fragile();

   }

   catch( NullPointerException npex ) 

   {  

      System.out.println( "NullPointerException thrown " );

   }

   catch( Exception ex ) 

      {  

         System.out.println( "Exception thrown " );

      }

   finally 

   {  

      System.out.println( "Done with exceptions " ); 

   }

   System.out.println( "myMethod is done" );

}

What is printed to standard output if fragile()

throws an IllegalArgumentException?

a) "NullPointerException thrown"

b) "Exception thrown"

c) "Done with exceptions"

d) "myMethod is done"

e) Nothing is printed

32. Consider the following code sample:

class Tree{}

class Pine extends Tree{}

class Oak extends Tree{}

public class Forest 

{  public static void main( String[] args ) 

   {  Tree tree = new Pine();

      if( tree instanceof Pine )

      System.out.println( "Pine" );

      if( tree instanceof Tree )

      System.out.println( "Tree" );

      if( tree instanceof Oak )

      System.out.println( "Oak" );

      else System.out.println( "Oops" );

   }

}

Select all choices that will be printed:

a) Pine

b) Tree

c) Forest

d) Oops

e) (nothing printed)

33. Consider the classes defined below:

import java.io.*;

class Super 

{

        int methodOne( int a, long b ) throws IOException 

        { // code that performs some calculations

    }

        float methodTwo( char a, int b )

        { // code that performs other calculations

    }

}

public class Sub extends Super

{

}

Which of the following are legal method

declarations to add to the class Sub? Assume that each method is the only one being added.

a) public static void main( String args[] ){}

b) float methodTwo(){}

c) long methodOne( int c, long d ){}

d) int methodOne( int c, long d ) throws

ArithmeticException{}

e) int methodOne( int c, long d ) throws

FileNotFoundException{}

34. Assume that Sub1 and Sub2 are both

subclasses of class Super.

Given the declarations:

Super super = new Super();

Sub1 sub1 = new Sub1();

Sub2 sub2 = new Sub2();

Which statement best describes the result of

attempting to compile and execute the following statement:

super = sub1;

a) Compiles and definitely legal at

runtime

b) Does not compile

c) Compiles and may be illegal at

runtime

35. For the following code:

class Super 

{  int index = 5;

   public void printVal() 

      {  System.out.println( "Super" );

      }

}

class Sub extends Super

{  int index = 2;

   public void printVal() 

   {  System.out.println( "Sub" );

   }

}

public class Runner 

{  public static void main( String argv[] ) 

   {  Super sup = new Sub();

      System.out.print( sup.index + "," );

      sup.printVal();

   }

}

What will be printed to standard output?

a) The code will not compile.

b) The code compiles and "5,

Super" is printed to standard output.

c) The code compiles and "5,

Sub" is printed to standard output.

d) The code compiles and "2,

Super" is printed to standard output.

e) The code compiles and "2,

Sub" is printed to standard output.

f) The code compiles, but throws an

exception.

36. How many objects are eligible for garbage

collection once execution has reached the line labeled Line A?

String name;

String newName = "Nick";

newName = "Jason";

name = "Frieda";

String newestName = name;

name = null;

//Line A

a) 0

b) 1

c) 2

d) 3

e) 4

37. Which of the following statements about

Java’s garbage collection are true?

a) The garbage

collector can be invoked explicitly using a Runtime object.

b) The finalize method is

always called before an object is garbage collected.

c) Any class that includes

a finalize method should invoke its superclass’ finalize method.

d) Garbage collection

behavior is very predictable.

38. What line of code would begin execution of a

thread named myThread?



39. Which methods are required to implement the interface Runnable.

a) wait()

b) run()

c) stop()

d) update()

e) resume()

40. What class defines the wait() method?



41. For what reasons might a thread stop execution?

a) A thread with higher priority

began execution.

b) The thread’s wait() method was invoked.

c) The thread invoked its yield() method.

d) The thread’s pause() method was invoked.

e) The thread’s sleep() method was invoked.

42. Which method below can change a String object, s ?

a) equals( s )

b) substring(

s )

c) concat(

s )

d) toUpperCase(

s )

e) none of the above will change s

43. If s1 is declared as:

String s1 =

"phenobarbital";

What will be the value of s2 after

the following line of code:

String s2 = s1.substring( 3, 5 );

1. a) null
   
   b) "eno"
   
   c) "enoba"
   
   d) "no"

   44. What method(s)
   
   from the java.lang.Math class might method() be if the statement

   method( -4.4 )
   
   == -4;

   is true.

   a)
   
   round()
   
   b) min()
   
   c) trunc()
   
   d) abs()
   
   e) floor()
   
   f) ceil()

   45. Which methods
   
   does java.lang.Math include for trigonometric computations?

   a)
   
   sin()
   
   b) cos()
   
   c) tan()
   
   d) aSin()
   
   e) aCos()
   
   f) aTan()
   
   g) toDegree()

   46. This piece of
   
   code:

   TextArea ta =

new TextArea( 10, 3 );

   Produces (select
   
   all correct statements):

   a)
   
   a TextArea with 10 rows and up to 3 columns
   
   b) a TextArea with a
   
   variable number of columns not less than 10 and 3 rows
   
   c) a TextArea that may not
   
   contain more than 30 characters
   
   d) a TextArea that can be
   
   edited

   47. In the list below, which subclass(es) of Component cannot be directly
   
   instantiated:

   a)
   
   Panel
   
   b) Dialog
   
   c) Container
   
   d) Frame

   48. Of the five Component methods listed below, only one is also a method
   
   of the class MenuItem. Which one?

   a)
   
   setVisible(
   
   boolean b )
   
   b) setEnabled( boolean b )
   
   c) getSize()
   
   d) setForeground( Color c )
   
   e) setBackground( Color c )

   49. If a font with
   
   variable width is used to construct the string text for a column, the
   
   initial size of the column is:

   a)
   
   determined by the number of characters in the string, multiplied by the
   
   width of a character in this font
   
   b) determined by the number of
   
   characters in the string, multiplied by the average width of a character
   
   in this font
   
   c) exclusively determined by the
   
   number of characters in the string
   
   d) undetermined

   50. Which of the
   
   following methods from the java.awt.Graphics class would be used to draw the outline of a
   
   rectangle with a single method call?

   a)
   
   fillRect()
   
   b)
   
   drawRect()
   
   c) fillPolygon()
   
   d) drawPolygon()
   
   e) drawLine()
   
   
   
   51. The Container methods add( Component comp ) and add( String name, Component comp) will throw an IllegalArgumentException
   
   if comp is a:
   
   
   
   a) button
   
   b) list
   
   c) window
   
   d) textarea
   
   e) container that contains
   
   this container
   
   52. Of the following AWT classes, which one(s) are responsible for implementing the components layout?
   
   
   
   a)
   
   LayoutManager
   
   b) GridBagLayout
   
   c) ActionListener
   
   d) WindowAdapter
   
   e) FlowLayout

   53. A component that should resize vertically but not horizontally should
   
   be placed in a:

   a)
   
   BorderLayout in the North or South location
   
   b) FlowLayout as the first
   
   component
   
   c) BorderLayout in the
   
   East or West location
   
   d) BorderLayout in the
   
   Center location
   
   e) GridLayout

   54. What type of object is the parameter for all methods of the
   
   MouseListener interface?

   55. Which of the following statements about event handling in JDK 1.1 and
   
   later are true?

   a)
   
   A class can implement multiple listener interfaces
   
   b) If a class implements a listener
   
   interface, it only has to overload the methods it uses
   
   c) All of the MouseMotionAdapter class
   
   methods have a void return type.

   56. Which of the
   
   following describe the sequence of method calls that result in a component
   
   being redrawn?

   a)
   
   invoke paint() directly
   
   b) invoke update which
   
   calls paint()
   
   c) invoke repaint() which invokes update(),
   
   which in turn invokes paint()
   
   d) invoke repaint() which invokes paint directly

   57. Which of these is a correct fragment within the
   
   web-app element of deployment descriptor. Select the two correct
   
   answer.

   1. 
      
      404
      
      /error.jsp
   2. 
      
      mypackage.MyException
      
      404
      
      /error.jsp
   3. mypackage.MyException
      
      404
   4. 
      
      mypackage.MyException
      
      /error.jsp

58. A

bean with a property color is loaded using the following statement


id="fruit" class="Fruit"/>

Which of the following statements may be used to set the of color

property of the bean. Select the one correct answer.

1.
id="fruit" property="color" value="white"/>

2.
name="fruit" property="color" value="white"/>

3.
name="fruit" property="color" value="white"/>

4.
name="fruit" property="color" value="white">

5.
name="fruit" property="color" value="white"/>

6.


property="color" value="white">

59. What gets printed when the following JSP code is

invoked in a browser. Select the one correct answer.

<%=

if(Math.random() <>

hello

<%=

} else { %>

hi

<%=

} %>

a.

The browser will print either hello or

hi based upon the return value of random.

b.

The string hello will always get

printed.

c.

The string hi will always get printed.

d.

The JSP file will not compile.

60. Given the following web application deployment descriptor:

MyServlet

...





myServlet

*.jsp

Which statements are true?

1) servlet-mapping element should be inside servlet element

2) url-pattern can’t be defined that way.

3) if you make the http call:

href="http://host/servlet/Hello.do">http://host/Hello.jsp the servlet container will execute MyServlet.

4) It would work with any extension excepting jsp,html,htm

61.Name the class that includes the getSession method that is used to get the HttpSession object.

1. HttpServletRequest
2. HttpServletResponse
3. SessionContext
4. SessionConfig

62. What will be the result of running the following jsp

file taking into account that the Web server has just been started and this is

the first page loaded by the server?

<%=

request.getSession(false).getId() %>

1)It won’t

compile

2)It will

print the session id.

3)It will produce a NullPointerException as the

getSession(false) method’s call returns null, cause no session had been

created.

4)It will

produce an empty page.

63. The

page directive is used to convey information about the page to JSP container.

Which of these are legal syntax of page directive. Select the two correct

statement

1. <% page info="test page" %>
2. <%@ page info="test page"
   
   session="false"%>
3. <%@ page session="true" %>
4. <%@ page
   
   isErrorPage="errorPage.jsp" %>
5. <%@ page isThreadSafe=true %>

64. Which

of the following are methods of the Cookie Class?

        1) setComment

        2) getVersion

        3) setMaxAge

        4) getSecure