Ans:
a) false
false
false
dar
b) false
true
false
Poddar
c) Compiler Error
d) true
true
false
dar
Correct Answer is a)
***** Look carefully at code and
answer the following questions ( Q2 to Q8)
1 import
java.applet.Applet;
2 import java.awt.*;
3 import
java.awt.event.*;
4 public class hello4 extends
Applet {
5 public void
init(){
6
add(new myButton("BBB"));
7 }
8 public void
paint(Graphics screen) {
9 }
10 class myButton
extends Button{
11
myButton(String label){
12
super(label);
13
}
14
public String paramString(){
15
return super.paramString();
16
}
17
}
18 public static void
main(String[] args){
19 Frame
myFrame = new Frame(
20
"Copyright Amit");
21
myFrame.setSize(300,100);
22 Applet myApplet = new
hello4();
23
Button b = new Button("My Button");
24 myApplet.add(b);
25
b.setLabel(b.getLabel()+"New");
26 // myButton b1 =(new
hello4()).new myButton("PARAMBUTTON");
27
System.out.println(b1.paramString());
28
myFrame.add(myApplet);
29
myFrame.setVisible(true);
30
myFrame.addWindowListener(new WindowAdapter(){
31
public void windowClosing(WindowEvent e){
32
System.exit(0);}});
33
}
34 } //End hello4 class.
Q2. If you run the above program
via appletviewer ( defining a HTML file), You see on screen.
a) Two buttons
b) One button with label as "BBB"
c) One button with label as "My
ButtonNew"
d) One button with label
as "My Button"
Correct answer is b)
Q3. In the above code if line 26 is uncommented and program runs as standalone application
a) Compile Error
b) Run time error
c) It will print the the label as PARAMBUTTON for
button b1
Correct answer is c)
Q4 In the code if you compile as
"javac hello4.java" following files will be generated.
a) hello4.class, myButton.class,hello41.class
b)hello4.class,
hello4$myButton.class,hello4$1.class
c)hello4.clas,hello4$myButton.class
Correct answer is b)
Q5. If above program is run as a standalone application. How many buttons will be displayed
a) Two buttons
b) One button with label as "BBB"
c) One button with label as "My ButtonNew"
d) One button with label as "My
Button"
correct answer is C)
Q6. If from line no 14 keyword "public" is removed, what will happen.( Hint :paramString() method in java.awt.Button is a protected method. (Assume line 26 is uncommented)
a) Code will not compile.
b) Code will compile but will give a run time
error.
c) Code will compile and no
run time error.
Correct answer is a). As you can not override a method with weaker access privileges
Q7. If from line no 14 keyword "public" is replaced with "protected", what will happen.(Hint :paramString() method in java.awt.Button is a protected method.(Assume line 26 is uncommented)
a) Code will not compile.
b) Code will compile but will give a run time
error.
c) Code will compile and no
run time error.
Correct answer is c) . As you can access a protected variable in the same package.
Q8.If line no 26 is replaced with Button b1 = new Button("PARAMBUTTON").(Hint :paramString() method in java.awt.Button is a protected method.(Assume line 26 is uncommented)
a) Code will not compile.
b) Code will compile but will give a run time
error.
c) Code will compile and no
run time error.
Correct answer is a) Because protected variables and methods can not be accssed in another package directly. They can only be accessed if the class is subclassed and instance of subclass is used.
Q9. What is the output of following if the return value is "the value 0 if the argument string is equal to this string; a value less than 0 if this string is lexicographically less than the string argument; and a value greater than 0 if this string is lexicographically greater than the string argument" (Assuming written inside main)
String s5 = "AMIT";
String s6 = "amit";
System.out.println(s5.compareTo(s6));
System.out.println(s6.compareTo(s5));
System.out.println(s6.compareTo(s6));
Ans
a> -32
32
0
b> 32
32
0
c> 32
-32
0
d> 0
0
0
Correct Answer is a)
Q10) What is the
output (Assuming written inside main)
String s1 = new
String("amit");
String s2 = s1.replace('m','i');
s1.concat("Poddar");
System.out.println(s1);
System.out.println((s1+s2).charAt(5));
a) Compile error
b) amitPoddar
o
c) amitPoddar
i
d) amit
i
Correct answer is d)As String is imutable.so s1 is always "amit". and s2 is "aiit".
Q11) What is the
output (Assuming written inside main)
String s1 = new
String("amit");
System.out.println(s1.replace('m','r'));
System.out.println(s1);
String s3="arit";
String s4="arit";
String s2 =
s1.replace('m','r');
System.out.println(s2==s3);
System.out.println(s3==s4);
a) arit
amit
false
true
b) arit
arit
false
true
c) amit
amit
false
true
d) arit
amit
true
true
Correct answer
is a) s3==s4 is true because java points both s3 and s4 to same memory
location in string pool
Q12) Which one does not extend
java.lang.Number
1)Integer
2)Boolean
3)Character
4)Long
5)Short
Correct answer is 2) and 3)
Q13) Which one does not have a
valueOf(String) method
1)Integer
2)Boolean
3)Character
4)Long
5)Short
Correct
answer is 3)
Q.14) What is the output of
following (Assuming written inside main)
String s1 = "Amit";
String s2 =
"Amit";
String s3
= new String("abcd");
String s4 = new
String("abcd");
System.out.println(s1.equals(s2));
System.out.println((s1==s2));
System.out.println(s3.equals(s4));
System.out.println((s3==s4));
a) true
true
true
false
b) true
true
true
true
c) true
false
true
false
Correct answer
is a)
Q15. Which checkbox will be
selected in the following code ( Assume with main and added to a Frame)
Frame myFrame = new Frame("Test");
CheckboxGroup cbg = new CheckboxGroup();
Checkbox
cb1 = new Checkbox("First",true,cbg);
Checkbox
cb2 = new Checkbox("Scond",true,cbg);
Checkbox
cb3 = new Checkbox("THird",false,cbg);
cbg.setSelectedCheckbox(cb3);
myFrame.add(cb1);
myFrame.add(cb2);
myFrame.add(cb3);
a) cb1
b) cb2,cb1
c) cb1,cb2,cb3
d) cb3
Correct Answer is d) As in a CheckboxGroup only one can be selected
Q16) Which checkbox will be
selected in the following code ( Assume with main and added to a Frame)
Frame myFrame = new Frame("Test");
CheckboxGroup cbg = new CheckboxGroup();
Checkbox
cb1 = new Checkbox("First",true,cbg);
Checkbox
cb2 = new Checkbox("Scond",true,cbg);
Checkbox
cb3 = new Checkbox("THird",true,cbg);
myFrame.add(cb1);
myFrame.add(cb2);
myFrame.add(cb3);
a) cb1
b) cb2,cb1
c) cb1,cb2,cb3
d) cb3
Correct Answer is d) As in a CheckboxGroup only one can be selected
Q17) What will be the output of
line 5
1 Choice
c1 = new Choice();
2 c1.add("First");
3
c1.addItem("Second");
4 c1.add("Third");
5
System.out.println(c1.getItemCount());
a) 1
b) 2
c) 3
d) None of the above
Correct Answer is c)
Q18) What will be the order of
four items added
Choice c1 = new Choice();
c1.add("First");
c1.addItem("Second");
c1.add("Third");
c1.insert("Lastadded",2);
System.out.println(c1.getItemCount());
a) First,Second,Third,Fourth
b)
First,Second,Lastadded,Third
c)
Lastadded,First,Second,Third
Correct ANswer is b)
Q19) Answer based on following
code
1 Choice c1
= new Choice();
2
c1.add("First");
3 c1.addItem("Second");
4 c1.add("Third");
5
c1.insert("Lastadded",1000);
6
System.out.println(c1.getItemCount());
a) Compile time error
b) Run time error at line
5
c) No error and line 6
will print 1000
d) No
error and line 6 will print 4
Correct ANswer is d)
Q20) Which one of the following does not extends java.awt.Component
a) CheckBox
b) Canvas
c) CheckbocGroup
d) Label
Correct answer is c)
Q21) What is default layout
manager for panels and applets?
a)
Flowlayout
b) Gridlayout
c) BorderLayout
Correct answer is a)
Q22) For awt components which of the following statements are true?
a) If a component is not explicitly assigned
a font, it usese the same font that it container uses.
b) If a component is not explicitly assigned a
foreground color , it usese the same foreground color that it container
uses.
c) If a component is not
explicitly assigned a backround color , it usese the same background color
that it container uses.
d) If a
component is not explicitly assigned a layout manager , it usese the same layout
manager that it container uses.
correct answer is a),b),c)
Q23)java.awt.Component class method getLocation() returns Point (containg x and y cordinate).What does this x and y specify
a) Specify the postion of components
lower-left component in the coordinate space of the component's parent.
b) Specify the postion of components
upper-left component in the coordinate space of the component's parent.
c) Specify the postion of components
upper-left component in the coordinate space of the screen.
correct answer is b)
Q24. What will be the output of
follwing
{
double d1 = -0.5d;
System.out.println("Ceil for d1 " +
Math.ceil(d1));
System.out.println("Floor for d1 "
+Math.floor(d1));
}
Answers:
a) Ceil for d1 0
Floor for d1 -1;
b) Ceil for d1 0
Floor for d1 -1.0;
c) Ceil for d1 0.0
Floor for d1 -1.0;
d) Ceil for d1 -0.0
Floor for d1 -1.0;
correct answer is d) as 0.0 is treated differently from -0.0
Q25. What is the output of
following
{
float f4 = -5.5f;
float f5 = 5.5f;
float f6 = -5.49f;
float f7 = 5.49f;
System.out.println("Round f4 is " +
Math.round(f4));
System.out.println("Round f5 is " +
Math.round(f5));
System.out.println("Round f6 is " +
Math.round(f6));
System.out.println("Round f7 is " +
Math.round(f7));
}
a)Round f4 is -6
Round f5 is 6
Round f6 is -5
Round f7 is 5
b)Round f4 is -5
Round f5 is 6
Round f6 is -5
Round f7 is 5
Correct answer is b)
Q26. Given Integer.MIN_VALUE =
-2147483648
Integer.MAX_VALUE = 2147483647
What is the output of following
{
float f4 = Integer.MIN_VALUE;
float f5 = Integer.MAX_VALUE;
float f7 = -2147483655f;
System.out.println("Round f4 is " +
Math.round(f4));
System.out.println("Round f5 is " +
Math.round(f5));
System.out.println("Round f7 is " +
Math.round(f7));
}
a)Round f4 is -2147483648
Round f5 is 2147483647
Round f7 is -2147483648
b)Round f4 is -2147483648
Round f5 is 2147483647
Round f7 is -2147483655
correct answer is a)
//Reason If the argument is negative infinity or any
value less than or equal to the value of Integer.MIN_VALUE, the result is
equal to the value of
Integer.MIN_VALUE.
If the argument is positive
infinity or any value greater than or equal to the value of Integer.MAX_VALUE,
the result is
equal to the value of
Integer.MAX_VALUE. // From JDK api documentation
Q27)
1 Boolean b1 = new
Boolean("TRUE");
2 Boolean b2 = new Boolean("true");
3 Boolean b3 = new
Boolean("JUNK");
4 System.out.println("" + b1 + b2 + b3);
a) Comiler error
b) RunTime error
c)truetruefalse
d)truetruetrue
Correct answer is c)
Q28) In the above question if line
4 is changed to
System.out.println(b1+b2+b3); The output is
a) Compile time error
b) Run time error
c) truetruefalse
d) truetruetrue
Correct answer is a) As there is no
method to support Boolean + Boolean
Boolean b1 = new
Boolean("TRUE");
Think
----->System.out.println(b1); // Is this valid or not?
Q29. What is the output
{
Float f1 = new Float("4.4e99f");
Float f2 = new Float("-4.4e99f");
Double d1 = new Double("4.4e99");
System.out.println(f1);
System.out.println(f2);
System.out.println(d1);
}
a) Runtime error
b) Infinity
-Infinity
4.4E99
c) Infinity
-Infinity
Infinity
d) 4.4E99
-4.4E99
4.4E99
Correct answer is b)
Q30 Q. Which of the following
wrapper classes can not
take a
"String" in constructor
1) Boolean
2) Integer
3) Long
4) Character
5) Byte
6) Short
correct answer is 4)
Q31. What is the output of
following
Double
d2 = new Double("-5.5");
Double d3 = new
Double("-5.5");
System.out.println(d2==d3);
System.out.println(d2.equals(d3));
a) true
true
b) false
false
c) true
false
d) false
true
Correct answer is d)
Q32) Which one of the following
always honors the components's preferred size.
a) FlowLayout
b) GridLayout
c) BorderLayout
Correct answer is a)
Q33) Look at the following
code
import
java.awt.*;
public class visual extends java.applet.Applet{
static Button b = new
Button("TEST");
public void init(){
add(b);
}
public
static void main(String args[]){
Frame f = new Frame("Visual");
f.setSize(300,300);
f.add(b);
f.setVisible(true);
}
}
What will happen if above code is run as a standalone application
a) Displays an empty frame
b) Displays a frame with a button covering the entire
frame
c) Displays a frame with a
button large enough to accomodate its label.
Correct answer is b) Reason- Frame uses
Border Layout which places the button to CENTRE
(By default) and ignores Button's preferred
size.
Q34 If the code in Q33 is
compiled and run via appletviewer what will happen
a) Displays an empty applet
b) Displays a applet with a button covering the
entire frame
c) Displays a applet
with a button large enough to accomodate its label.
Correct answer is c) Reason- Applet uses FlowLayout which honors Button's preferred size.
Q35. What is the output
public static void
main(String args[]){
Frame f = new
Frame("Visual");
f.setSize(300,300);
f.setVisible(true);
Point p = f.getLocation();
System.out.println("x is " + p.x);
System.out.println("y is " + p.y);
}
a) x is 300
y is 300
b) x is 0
y is 0
c) x is 0
y is 300
correct answer is b) Because postion is
always relative to parent container and in this
case Frame f is the topemost
container
Q36) Which one of the following
always ignores the components's preferred size.
a) FlowLayout
b) GridLayout
c) BorderLayout
Correct answer is b)
Q37) Consider a directory
structure like this (NT or 95)
C:\JAVA\12345.msg
--FILE
\dir1\IO.class -- IO.class is under dir1
Consider the following code
import java.io.*;
public class IO {
public static void main(String args[]) {
File f = new File("..\\12345.msg");
try{
System.out.println(f.getCanonicalPath());
System.out.println(f.getAbsolutePath());
}catch(IOException e){
System.out.println(e);
}
}
}
What will be the output of running "java IO"
from C:\java\dir1
a)
C:\java\12345.msg
C:\java\dir1\..\12345.msg
b) C:\java\dir1\12345.msg
C:\java\dir1\..\12345.msg
c) C:\java\dir1\..\12345.msg
C:\java\dir1\..\12345.msg
correct answer is a) as
getCanonicalPath Returns the canonical form of this File object's pathname. The
precise definition of canonical form is system-dependent, but it usually
specifies an absolute pathname in which all
relative references and references to the current user directory have been
completely resolved.
WHERE AS
getAbsolutePath Returns the absolute
pathname of the file represented by this object. If this object represents an
absolute pathname, then return the pathname. Otherwise, return a pathname that
is a concatenation of the current user directory, the separator character, and
the pathname of this file object.
Q38) Suppose we copy IO.class
from C:\java\dir1 to c:\java
What will be the
output of running "java IO" from C:\java.
a) C:\java\12345.msg
C:\java\..\12345.msg
b) C:\12345.msg
C:\java\..\12345.msg
c) C:\java\..\12345.msg
C:\java\\..\12345.msg
correct answer is b)
Q39) Which one of the following methods of java.io.File throws IOException and why
a) getCanonicalPath and getAbsolutePath both
require filesystem queries.
b) Only
getCannonicalPath as it require filesystem queries.
c) Only getAbsolutePath as it require filesystem
queries.
Correct answer is b)
Q40) What will be the output
if
Consider a
directory structure like this (NT or 95)
C:\JAVA\12345.msg --FILE
\dir1\IO.class -- IO.class is under dir1
import java.io.*;
public class IO {
public static void main(String args[]) {
File f = new File("12345.msg");
String arr[] = f.list();
System.out.println(arr.length);
}
}
a) Compiler error as 12345.msg is a file not
a directory
b)
java.lang.NullPointerException at run time
c) No error , but nothing will be printed on
screen
Correct ansewer is b)
Q41) What will be the
output
Consider a
directory structure like this (NT or 95)
C:\JAVA\12345.msg --FILE
import java.io.*;
public class IO {
public static void main(String args[]) {
File f1 =
new File("\\12345.msg");
System.out.println(f1.getPath());
System.out.println(f1.getParent());
System.out.println(f1.isAbsolute());
System.out.println(f1.getName());
System.out.println(f1.exists());
System.out.println(f1.isFile());
}
}
a) \12345.msg
\
true
12345.msg
true
true
b) \12345.msg
\
true
\12345.msg
false
false
c) 12345.msg
\
true
12345.msg
false
false
d) \12345.msg
\
true
12345.msg
false
false
correct answer is d)
Q42) If in question no 41 the
line
File
f1 = new File("\\12345.msg"); is replaced with File f1 = new
File("12345.msg");
What will be the
output
a) 12345.msg
\
true
12345.msg
true
true
b) 12345.msg
null
true
12345.msg
true
true
c)
12345.msg
null
false
12345.msg
true
true
d) \12345.msg
\
true
12345.msg
false
false
Correct answer is c)