JAVA Multiple choice Questions

JAVA

1. How do you create a Reader object from an inputstream object?

a. use the static createReader() method of the inputstream class.

b. use the static createReader() method of the reader class

c. create an inputstreamreader object, passing the inputstream object as an argument to the inputstreamreader constructor

d. create an outputstreamreader object, passing the inputstream object as an argument to the outputstreamreader constructor.

2. which of the following are valid identifiers?

a. _id

b. $id

c. #id

d. -id

3. which of the following are true?

a. the sleep() method puts a thread in the ready state.

b. the yield() method puts a thread in the waiting state.

c. the suspend() method is the preferred method for stopping a thread's execution.

d. a thread's interrupt() method results in the throwing of the interruptedexception.

4. which of the following classes have a paint() method?

a. canvas

b. image

c. frame

d. graphics

5. which statement creates textarea with 10 rows and 20 columns?

a. new TextArea(10,20)

b. new TextArea(20,10)

c. new TextArea(Rows(10),Cols(20))

d. new TextArea(Row(10),Col(20))

6. which of the following are true?

a. the AWT automatically causes a window to be repainted when a portion of a window has been minimized and then maximized.

b. the AWT automatically causes a window to be repainted when a portion of a window has been covered and then uncovered.

c. the AWT automatically causes a window to be repainted when application data is changed.

d. the AWT does not support repainting operations.

7. which of the following are java keywords?

a. null

b. NULL

c. extends

d. main

8. which of the following thread state transitions are valid?

a. from ready to running

b. from running to ready

c. from running to waiting

d. from waiting to running

e. from waiting to ready

f. from ready to waiting

9. which of the following is not a wrapper class?

a. string

b. integer

c. boolean

d. character

10. which is the advantage of encapsulation?

a. only public methods are needed

b. no exceptions need to be thrown from any method

c. making the class final causes no cnsequential changes to other code.

d. it changes the implementation without changing the interface and causes no consequential changes to other code.

e. it changes the interface without changing the implementatino and causes no consequential changes to other code.

11. which font attributes are available through the FontMetrics class?

a. ascent

b. leading

c. case

d. height

12.which of the following are true?

a. component extends container

b. menuitem extends component

c. container extends component

d. menucomponent extends component

13. what is the ovtal equivalent of the decimal value 123?

a. 0173

b. 123

c. 0x123

d. 0x173

14. in order for the public class Myclass to successfully compile, which of the following are true?

a. myclasss must have a correctly formed main method

b. myclass must be defined in the file myclass.java

c. myclass must be defined in the myclas package.

d. myclass must be imported

15. which of the following are true?

a. any unicode character is represented using 16 bits

b. seven bits are needed to represent any ASCII character

c. UTf-8 characters are represented using only eight bits.

d. UTF-16 characters are represented using only 16 bits.

16. which of the following are true about a dead thread?

a. the thread's object is discarded.

b. the thread must wait until all other threads execute before it is restarted

c. the thread cannot be restarted

d. the thread is synchornized

17. what is the output displayed by the following program?

class  question {

public static void main(String args[]) {

int n=7;

n<<=3;

n=n&n+1|n+2^n+3;

n>>=2;

System.out.println(n);

}

}

a. 0

b. -1

c. 14

d. 64

18. which of the following are true?

a. a component may handle its own events by adding itself as an even listener

b. a component may handle its own events by overriding its event-dispatching method.

c. a component may not handle its own events

d. a component may handle its own events only if it implements the handleEvent() method

19. what can contain objects that have a unique key field of string type, if it is required to retrieve the objects using that key field as an inded?

a. map

b. set

c. list

d. collection

e. enumeration

20. what output is displayed by the following program?

import java.io.*;

public class TestIOApp {

public static void main(String args[]) throws IOException{

StringReader stringin = new StringReader("test")

LineNumberReader in = new LineNumberReader(stringin);

PrintWriter out = new PrintWriter(System.out);

out.println(in.readLine());

out.flush();

}

}

a. test

b. 1. test

c. 1: test

d. 1 test

21. which of the following are characteristic of a fully encapsulated class?

a. all variables are private

b. all methods are private

c. methods are provided to access the class's properties

d. the class's design may be changed with minimal impact on its implementation

22. which of the following are true about the finally clause of a try-catch-finally statement?

a. it is only executed after a catch clause has executed

b. it is only executed if a catch clause has not executed

c. it is always executed unless its thread terminates

it is only executed if an exception is thrown

23. which layout stacks components on tope of each other?

a. cardlayout

b. null layout

c. borderlayout

d. setlayout

24. which of the following components generate action events?

a. buttons

b. labels

c. checkboxes

d. windows

25. which methods will cause a frame to be displayed?

a. show()

b. setVisible()

c. display()

d. displayFrame()

26. what is the range of the short type?

a. 0 to 2^16

b. -(2^16) to 2^16

c. -(2^15) to 2^15

d. -(2^15) to 2^15-1

27. what is the value of a[3] as the result of the following array declaration?

int[] a={1,2,3,4,5};

a.1

b.2

c.3

d.4

28. whati s the output of the following program?

public class question {

public static void main(String args[]) {

boolean[] b = new boolean[2];

double[] d = new double[2];

System.out.print(b[0]);

System.out.println(d[1]);

a. true0.0

b. true0

c. false0.0

d. false0

29. what is the output of the following program?

class question {

static int i=1,j=2;

static {

display(i);

}

public static void main(String args[]) {

display(j);

static void display(int n) {

system.out.print(n);

}

}

a. 1

b. 2

c. 12

d. 21

30. which of the following are true?

a. a top-level class may be declared as private

b. a method may be declared as transient

c. a constructor may be declared as volatile

d. a local variable may be declared as final

31. when two or more objects are added as listners for the same event, which listener is first invoked to handle the event?

a. the first object that was added as a listener

b. the last object that was added as a listener

c. there is no way to determine which listener will be invoked first.

it is impossible to have more than one listener for a given event.

32. which of the following are true?

a. a reference to an array can be cast to a reference to an object

b. a reference to an array can be cast to a reference to a cloneable

c. a reference to an array can be cast to a reference to a string

d. none of the above

33. which layout is used to layout the components of a container in a grid where each row and column are the same size?

a. gridlayout

b. null layout

c. gridbaglayout

d. gridbagconstraintlayout

34. what is the output of the following program?

class outer {

string s = "outer";

public static void main(string args[]) {

new outer().new Inner();

}

outer() {

system.out.prints(s);

}

class inner {

string s = "inner";

inner() {

system.out.print(s);

}

}

}

a. outer

b. inner

c. outerinner

d. innerouter

35. what is the result of the expression 5.4 + "3.2" ?

a. the double 8.6

b. the string 8.6

c. the long value 8

d. the string 5.43.2

36. which are true about the container class?

a. the validate() method is used to cause a container to be laid out and redisplayed

b. the add() method is used to add a component to a container

c. the getborder() method returns information about a containers insets

d. the getcomponent() method is used to access a component that is contained in a container

37. which of the following are true about this method declaration?

void mymethod(string s) { }

a. mymethod() is static

b. mymethod does not return a value

c. mymethod is abstract

d. mymethod may not be accessed outside of a package in which it is declared

38. which lines of output are displayed by the following program?

class question{

public static void main(string[] args) {

for(int i=0;i<10;i++) {

try {

try {

if (i%3==0) throw new Exception("E0");

system.out.println(i);

}

catch(exception inner) {

i *=2;

if(i%3==0) throw new exception("E1");

} finally {

++i;

}

}

catch(exception outer) {

i+=3;

} finally {

--i;

}

}

}

}

a. 4

b. 5

c. 6

d. 7

e. 8

f. 9

39. if you run the following program, what lines would be included in its output?

class question{

public static void main(string args[]) {

int i,j;

for(i=0,j=0;i+j<20;++i,j+=i--) {

system.out.println(i+j);

}

}

}

a. 5

b. 8

c. 13

d. the program cannot be compiled because the for statement's syntax is incorrect.

40. which of the following are direct or indirect subclasses of component?

a. button

b. label

c. checkboxmenuitem

d. toolbar

e. frame

41. which layout is the defauld layout of a panel object?

a. gridlayout

b. flowlayout

c. gridlinelayout

d. linelayout

43. which of the following are true?

a. java only supports preemptive scheduling.

b. java only supports time slicing.

c. the jvm has been implemented on os that use time slicing

d. the jvm has been implemented on os that use preemptive scheduling.

44. what should you use to position a button within an application frame so that the size of the button is not affected by the frame size?

a. flowlayout

b. gridlayout

c. the center area of a borderlayout

d. the east or west area of a borderlayout

e. the north or south area of a borderlayout

45. a catch clause may catch exceptions of which types?

a. thowable type

b. error type

c. exception

d. string

46. what is the value displayed by the following program?

class question{

public static void main(string[] args) {

int x=0;

boolean b1,b2,b3,b4;

b1= b2= b3= b4= true;

x = (b1|b2&b3^b4)?x++:--x;

system.out.println(x)

}

}

a. 0

b. -1

c. 1

d. none of the above

47. which method is used to set the text of a label object?

a. settext()

b. setlabel()

c. settextlabel()

d. setlabeltext()

48. which of the following methods cause the string object referenced by s to be changed?

a. s.concat()

b. s.touppercase(0

c. s.replace()

d. none of the above

49. in order for teh myprogram proram to be compiled and run, which of the followin must be true?

a. the myprogram class must be defined in myprogram.java

b. myprogram must be declared as public

c. myprogram must have correctly formed main() method

d. myprogram must import java.lang

50.  which of the followin are true?

a. textcomponent extends textarea

b. textarea extends textfield

c. textfield extends textcomponent

d. textcomponent extends textfield

d. textarea extends textcomponent

51. what is the value of 111%13?

a. 11

b. 5

c. 6

d. 7

52. which of the following are methods of the graphics class?

a. drawrect()

b. drawimage()

c. drawpoint()

d. drawstring()

53. if you run the following program, which lines would be included in its output?

class question {

public static void main(string[] args) {

int i=1;

int j=2;

outer: while(i<j) {

++i;

inner: do {

++j;

if (j%3==0) continue outer;

if (i%3==0) break inner;

if (i%3==1) break outer;

system.out.println(i*j);

} while (j < i);

system.out.println(i+j);

}

}

}

a. 5

b. 6

c. 7

d. the program does not display any output.

54. what is the output of the following program?

class s1{

public static void main(string[] args) {

new s2();

}

s1() {

system.out.pritn("s1");

}

}

class s2 extends s1 {

s2() {

system.out.print("s2");

}

}

a. s1

b. s2

c. s1s2

d. s2s1

55. what is the range of char type?

a. 0 to 2^16

b. 0 to 2^16-1

c. 0 to 2^15

d. 0 to 2^15-1

56. which of the following methods are methods of math class?

a. absolute()

b. cosine()

c. sine()

d. log()

57. which of the following are true about local inner classes?

a. they are not associated with any instance of an outer class.

b. they may access final initialized variables and parameters that are in the scope of the statement block in which the class is declared

c. they may be declared public, protected or private

d. they may not implement an interface

58. when a thread blocks on I/O, which of the following are true?

a. the thread enters the ready state.

b. the thread enters the dead state

c. no other thread may perform I/O

d. the thread enters the waiting state

59. what is the output of the following program when it is invoked using the command line java Test this is a test?

class Test {

public static void main(String arg[]) {

system.out.println(arg[1]);

}

}

a. this

b. is

c. a

d. test?

60. a frame's background color is set to color.yellow and button's background color is set to colr.blue. suppose the button is added to a panel, which is added to the frame. what background color will be used wth the panel?

a. color.yellow

b. color.blue

c. color.green

d. color.white

1. What releases of Java technology are currently available? What do they contain?

The Java programming language is currently shipping from Sun Microsystems, Inc. as the Java Development Kit (JDKTM). All Sun releases of the JDK software are available from the JDK software home page (http://java.sun.com/products/jdk/).

Each release of the Java Development Kit (JDK) contains:

·       Java Compiler

·       Java Virtual Machine*

·       Java Class Libraries

·       Java AppletViewer

·       Java Debugger and other tools

·       Documentation (in a separate download bundle)

To run Java 1.0 applets, use Netscape Navigator 3.x or other browsers that support Java applets. To run Java 1.1.x applets, use HotJavaTM 1.x or Netscape Navigator 4.x or other browsers that support the newest version of the Java API.

2. What are the security problems I've heard about JavaScript technology scripts?

JavaScript technology is a scripting language used with Netscape Navigator. There have been reports of privacy problems with JavaScript technology, and Netscape is committed to addressing those concerns. JavaScript technology cannot be used to invoke Java applets. The privacy problems reported with JavaScript technology are not present in Java applets.

3. Why developers should not write programs that call 'sun' packages

Java Software supports into the future only classes in java.* packages, not sun.* packages. In general, API in sun.* is subject to change at any time without notice. For more details, see the article Why Developers Should Not Write Programs That Call 'sun' Packages.

4. Where did the Java name come from? What does it stand for?

The name was chosen during one of several brainstorming sessions held by the Java software team. We were aiming to come up with a name that evoked the essence of the technology -- liveliness, animation, speed, interactivity, and more. "Java" was chosen from among many, many suggestions. The name is not an acronym, but rather a reminder of that hot, aromatic stuff that many programmers like to drink lots of.

Source: www.technicalsymposium.com