Questions and Answers to Java Test (Recalled from the Certification Exam)
Test Questions recalled Date of Exam : 07/02/00
1. Float a = new Float(10.0F);
Float b = new Float(10.0F);
Long c = new Long(10L);
which one is true
a) a == b
b) a.equals(b)
c) a.equals(c)
d) a.equals(new Float(10.0F))
Answer: B & D
2. From given code, which are possible values for 'a' to print "test2" in output
if (a >4)
System.out.println("test1");
Else if (a >9)
System.out.println("test2");
Else
System.out.println("test3");
a.less than 0
b.less than 4
c.between 4 and 9
d.greater than 9
e.none
Answer: E
3. Choose the correct sentence for fully encapsulated class
a.All member variables are private
b.All member variables declared private and provide
public accessor methods for each variable.
c.Declare all variables without any access modifier.
e.Make all the methods private
Answer: B
4.You have a method in a class whose implementation you don't
want to change although you want to allow the class to be inherited
and used freely. What keyword would u use in the method declaration?
Answer: final
5.Choose correct declarations of two dimensional String array
a.String[][] a = String[20][20]
b.String[][] a = new String[20,20]
c.String[][] a = new String[20][20]
d.String a[][] = new String[20][20]
e.String[] a[] = new String[20]20]
Answer: C,D & E
6.Quesion on identifiers like Choose Correct identifiers
a.thisString
b.%var
c._toString
d._4_
Answer : A,C & D
7.choose the correct statement about gridbag layout
a.The weightx & weighty should have values between 0.0 & 1.0
b.If you specify the fill field is BOTH, there is no meaaning to set anchor field
c.If you specify anchoe field there is no meaning to set fill field is BOTH
Like this
Ans A
8.A question on Garbage collecting like it wiil ask you where the particlular
object exactly available to garbage collection
after line3
after line4
after line5
like this
9.What is the return type of main function which is the starting point of class
Ans void
10.Choose the Java key words from below
a.NULL
b.sizeof
c.extends
d.synchronized
Answer : C & D
11.Employee is a person. Employee has some info stored in vector,
no. of dependants, a flag tells is he IT asesse or not
Write a primary declaration for employee class by using the below words
public
Person
Employee
Vector
Boolean
int
class
extends
Ans : public class Employee extends Person
12.FilterInputStream is base class for BufferedInputStream and DataInputStream.
Choose the correct one which is the correct argument for the FilterInputStream
a.file
b.OutputStream
c.RandomAccessFile
d.InputStream
Answer : D
13.If you want to make your component to activate for user events,
choose the statements which are correct
a.you can add listener interfaces to this component
b.If you add multiple listeners they will become friendly to each other
c.You can add multiple interfaces to the component for different events
d.If listeners added, user can choose and implement only those methods what he needs
e.The component which is derived from awt.component is not listen the events for it self.
Answer : A,C
14.Choose the correct one about thread
a.The threads from one class ends at same time
b.when JVM exits the main method, it will stop only after all the threads are stopped.
c.If there are multiple threads , reading or writing of data of class is inconsistant
d.Programmer has to write a special programe for garbage collection in multiple threads
Answer B & C
15. Parent p = new Parent();
Child1 c1 = new Child1();
Child2 c2 = new Child2();
Child1 s = (Child1) new Parent;
Which one is correct
a)legal at compile time but illegal at runtime
b)illegal at compile time and runtime
c)illegal at compile time but legal at runtime
d)legal at compile time and runtime
Answer : A
16.Which one is valid for declaring the automatic variable
(method local variables)
public
final
static
Answer: final
17.which is java modifier to use method declaration
prevents to use 'this' in the method
Answer: static
18 from given code, which are possible values for 'a' to print
"test3" in output
if (a >4)
System.out.println("test1");
Else if (a >9)
System.out.println("test2");
Else
System.out.println("test3");
a.less than 0
b.less than 4
c.between 4 and 9
d.greater than 9
e.none
Answer : B
19. Range of the int
20. Range of the char
21. Parameters for main method in Java :
Answer : String [] arv
22. Interface with out order, duplicate and with out any search key.
: Set
23.
Public class MyClass{
Float x, float y;
Int z;
public MyClass(float a, float b)
{
x= a;
y=b;
}
public MyClass(float a,float b, int c)
{
// write code to do what MyClass (float a,float b ) is doing
z =c;
}
Answer : this(a,b)
24. write the code in Hex for 7
Answer : 0x07
25. Polygon is a Shape. This class has to access from any where is
the program..
Answer: public class Polygon extends Shape
26. String s = "Test"; Select all correct ans.
1. char c = "s";
2. s= s.append("For ")
3. s.length();
4. s.trim();
5. s = "For " + s;
Answer : 3,4 & 5
trim() returns the trimmed string so the output needs to be
assigned to another string as in :- s=s.trim();
27. In design the employee has the tasks in vector, Joining Date and
no. of depends. So following fields should be available in the class
of employee.
String
Vector
Date
Int
Float
Person
28. All the methods in Listener Interfaces should be
private
public
protected
undefined (friendly)
static
final
29. >> and >>> are
a.unsigned right shift and right rotate
b.unsigned right shift and signed right shift.
c.signed right shift and unsigned right shift.
d.Signed left shift and unsigned right shift.
e.signed left shift and unsigned left shift.
Answer : C
30 Best way to read the file as Strings.
Like
DataInputStream dis = new DataInputStream (new FileInputStream("test.txt"));
BufferedInputStream bis = new BufferInputStream (new FileInputStream("test"));
31.The parameter as to be passed for FilterInputStream.
File
String
Empty
FileReader
InputStream
32. Which of the following statements is true about the above code?
import java.awt.*;
import java.awt.event.*;
public class fram extends Frame
{
public static void main(String arg[])
{
fram f=new fram();
String msg="hello";
Button b=new Button("Click");
b.addActionListener(
new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
System.out.println(msg);
}
}
);
f.add(b);
f.pack();
f.show();
}
}
a.The code will not compile complaining that no layout has been
defined for the frame.
b.The code compiles and doesn't display anything.
c.The code runs and shows a single button occupying the whole frame.
On clicking the button you get the message "hello" at the Std o/p.
d.The code does not compile complaining about the inaccessibility of
a certain variable.
e.The code doesn't compile complaining that the constructor for fram
has not been defined.
Answer : D
the compilation error is
"Attempt to use a non-final variable msg from a different
method.From enclosing blocks, only final local variables are available.
System.out.println(msg);
^
"
33. Which of the following ?
1. public class sb
2.{
3. static public void main(String jk[])
{
StringBuffer s1=new StringBuffer("Hello");
StringBuffer s2=new StringBuffer("Hello");
meth(s1,s2);
System.out.println(s1+"\n"+s2);
}
private static void meth(StringBuffer s1,StringBuffer s2)
{
s2.append(" there");
s1=s2;
}
}
a.The code doesn't compile; it complains at line 3.
b.The code runs and produces O/p : Hello
Hello
c.The code runs and produces O/p : Hello
Hello there
d.The code runs and produces O/p : Hello there
Hello there
e.The code fails to compile saying the method meth is
declared private and is not accessible.
Answer : C
34. Which of the following?
class exSuper
{
public void func(String p,String s)
{
System.out.println(p);
}
}
public class example extends exSuper
{
public void func(String p,String s)
{
System.out.println(p+ " : " +s);
}
static public void main(String arg[])
{
exSuper e1=new exSuper();
e1.func("hello1","hi1");
exSuper e2=new example();
e2.func("hello2","hi2");
}
}
a.The code compiles and produces O/p : hello1 h1
hello2 hi2
b.The code compiles and produces O/p : hello1
hello2 hi2
c.The code compiles and produces O/p : hello1
hello2
d.The code compiles and produces O/p : hello1 h1
hello2
e.The code doesn't compile
Answer : B