1) What
is the size of a Char?
a)
4 bits
b)
7 bits
c)
8 bits
d)
16 bits - correct answer
2) A
class cannot be declared:
a)
Static
b)
Private - correct answer
c)
Default
3) Following
code will result in: int a = 3.5;
a)
Compilation error - correct answer
b)
Runtime error
c)
a being 3.5
d)
a being 3.
4) Following
code will result in: int a1 = 5; double a2 = (float)a1;
a)
Compilation error
b)
Runtime error
c)
No errors - correct answer
5) Following
code will result in: int a = 9/0;
a)
Compilation error: Divisions must be in a try block.
b)
Compilation error: DivideByZeroException
c)
Runtime Exception - correct answer
d)
No Error: a is NaN
6) Following
code will result in: float a = 9/0;
a)
Compilation error: Divisions must be in a try block
b)
Compilation error: DivideByZeroException
c)
Runtime Exception - correct answer
d)
No Error: a is NaN
7) A
class can be transient
a)
True
b)
False - correct answer
8) Following
code will result in: class A { int b = 1; public static void
main(String [] args) { System.out.println("b is " + b);
}}
a)
Compilation error - correct answer
b)
Runtime Error
c)
Runtime Exception
d)
Output of b is 1
9) Following
code will result in: class A { public static void main(String []
args) {B b = new A(); }} class B extends A {}
a)
Compile error - correct answer
b)
Runtime Exception
c)
No error
10) Following
code will result in: class A { public static void main(String []
args) {A a = new B(); }} class B extends A {}
a)
Compiler error
b)
Runtime Exception
c)
No errors - correct answer
11) Methods
that are marked protected can be called in any subclass of that
class.
a)
True - correct answer
b)
False
12) An
abstract class can have non-abstract methods.
a)
True - correct answer
b)
False
13) Java
keywords are written in lowercase as well as uppercase.
a)
True
b)
False - correct answer
14) What
is an instanceof
a)
A methods in object
b)
An operator and keyword - correct answer
15) Primitive
datatypes are allocated on a stack.
a)
True - correct answer
b)
False
16) Can
you compare a boolean to an integer?
a)
Yes
b)
No - correct answer
17) If
class A implements an interface does it need to implement all
methods of that interface?
a)
Yes, always.
b)
No, not when A is abstract - correct answer
18) Integer
a = new Integer(2); Integer b = new Integer(2); What happens when
you do if (a==b)?
a)
Compiler error
b)
Runtime Exception
c)
True
d)
False - correct answer
19) The
methods wait(), notify() and notifyAll() in Object need to be
called from synchronized pieces of code.
a)
True - correct answer
b)
False
20) Inner
classes can be defined within methods.
a)
True - correct answer
b)
False
21) Synchronized
is a keyword to tell a Thread to grab an Object lock before
continuing execution.
a)
True - correct answer
b)
False
22) The
default statement of a switch is always executed.
a)
True
b)
False - correct answer
23) How
can you prevent a member variable from becoming serialized?
a)
By marking it private
b)
By marking it volatile
c)
By marking it transient - correct answer
d)
You can not.
-----------------------------Second random java programming test answers--------------
The code will fail to compile
11 12
11 11
12 12
Question 1 What is the java.net.IDN class in 1.6?
Methods to
resolve integrated domain names (IDNs), such domain names are special
embedded names
Methods to swap bytes between network byte order and host byte order
Methods to convert internationalized domain names (IDNs) between a normal Unicode representation and an ASCII Compatible Encoding (ACE) representation
This class does not exist
None of the above
Methods to swap bytes between network byte order and host byte order
Methods to convert internationalized domain names (IDNs) between a normal Unicode representation and an ASCII Compatible Encoding (ACE) representation
This class does not exist
None of the above
{
public static void main (String args[]) throws Exception
{
Test o = new Test ();
System.out.println (o.content ());
}public String content () throws Exception
{throw new Exception ("This is an exception on this.content ()");
}private static class B
{public String content ()
{return ''B'';
}
}private static class A extends B
{public String content ()
{return ''A'';
}
}
}
The code will fail to compile
The code will compile but throw an exception at runtime
The code will compile and on running, it will print ''A''
The code will compile and on running, it will print ''B''
public static void main (String args[]) throws Exception
{
Test o = new Test ();
System.out.println (o.content ());
}public String content () throws Exception
{throw new Exception ("This is an exception on this.content ()");
}private static class B
{public String content ()
{return ''B'';
}
}private static class A extends B
{public String content ()
{return ''A'';
}
}
}
The code will fail to compile
The code will compile but throw an exception at runtime
The code will compile and on running, it will print ''A''
The code will compile and on running, it will print ''B''
Question
3 Which
of these interfaces are used by implementations of models for JTable?
TableModel
TableColumnModel
TableSelectionModel
ListModel
TableColumnModel
TableSelectionModel
ListModel
5
8
4
Any number of times
8
4
Any number of times
Question
5 One
method in your application needs
to be synchronized. Which of the following options are correct for
synchronization?
public
synchronized void Process(void){}
public void Process(){ synchronized(this){ } }
public void synchronized Process(){}
public synchronized void Process(){}
public void Process(){ synchronized(this){ } }
public void synchronized Process(){}
public synchronized void Process(){}
Question
6 What could be the replacement of "//ABC" in the
following code?public class Jam
{
public void apple(int i, String s)
{}
//ABC
}
public void apple(String s, int i){}
public int apple(int i, String s){}
public void apple(int i, String mystring){}
public void Apple(int i, String s) {}
public void apple(int i, String s)
{}
//ABC
}
public void apple(String s, int i){}
public int apple(int i, String s){}
public void apple(int i, String mystring){}
public void Apple(int i, String s) {}
Question
7 What will be the output when the following code is compiled
and run?public class Test
{
public static void main (String args[])
{
int i;
i = 3;
System.out.println ((int)i * 2.5 / 3.0);
}
}
The code will compile, but it will throw an exception when it is run
The code will compile and it will not produce any output when it is run
The code will fail to compile
The code will print 3
The code will print 2.5
The code will print 2
public static void main (String args[])
{
int i;
i = 3;
System.out.println ((int)i * 2.5 / 3.0);
}
}
The code will compile, but it will throw an exception when it is run
The code will compile and it will not produce any output when it is run
The code will fail to compile
The code will print 3
The code will print 2.5
The code will print 2
Question
8 What would happen on trying to compile and run the following
code?public class MainCls
{
public static void main(String argv)
{
System.out.println("My Text");
}
}
A compile error will be generated because 'main' is a reserved word and cannot be used for a class
"My Text" will be displayed
The code will compile. A runtime error will occur because 'main' is not properly defined
The code will compile. A runtime error will occur because constructor is not defined
public static void main(String argv)
{
System.out.println("My Text");
}
}
A compile error will be generated because 'main' is a reserved word and cannot be used for a class
"My Text" will be displayed
The code will compile. A runtime error will occur because 'main' is not properly defined
The code will compile. A runtime error will occur because constructor is not defined
Question
9 What will be the output when this code is compiled and
run?public class Test
{
static int x = 10;
public Test ()
{
Bar b = new Bar ();
Bar b1 = new Bar ();
update (b);
update (b1);
}private void update (Bar bar)
{
bar.x = ++x;
System.out.println (bar.x);
}public static void main (String args[])
{File f = new File("/","autoexec.bat"); b.DataInputStream d = new DataInputStream(System.in);c.RandomAccessFile r = new RandomAccessFile("OutFile"); d.OutputStreamWriter o = newOutputStreamWriter(System.out);
}private class Bar
{public int x = 10;
}
}
static int x = 10;
public Test ()
{
Bar b = new Bar ();
Bar b1 = new Bar ();
update (b);
update (b1);
}private void update (Bar bar)
{
bar.x = ++x;
System.out.println (bar.x);
}public static void main (String args[])
{File f = new File("/","autoexec.bat"); b.DataInputStream d = new DataInputStream(System.in);c.RandomAccessFile r = new RandomAccessFile("OutFile"); d.OutputStreamWriter o = newOutputStreamWriter(System.out);
}private class Bar
{public int x = 10;
}
}
The code will fail to compile
11 12
11 11
12 12
Question
10 Which
of the following statement will not compile?
File f = new
File("/","autoexec.bat");
DataInputStream d = new DataInputStream(System.in);
RandomAccessFile r = new RandomAccessFile("OutFile");
OutputStreamWriter o = new OutputStreamWriter(System.out);
DataInputStream d = new DataInputStream(System.in);
RandomAccessFile r = new RandomAccessFile("OutFile");
OutputStreamWriter o = new OutputStreamWriter(System.out);
Question
11 Which
of the following are "keywords" in Java?
default
NULL
String
throws
NULL
String
throws
Question
12 Which
of the following statements is true of the HashMap class?
It stores
information as key/value pairs
Elements are returned in the order they were added
It does not permit null keys
It does not permit null values
Elements are returned in the order they were added
It does not permit null keys
It does not permit null values
Question
13 How
does the set collection deal with duplicate elements?
Duplicate
values will cause an error at compile time
A set may contain elements that return duplicate values from a call to the equals method
An exception is thrown if you attempt to add an element with a duplicate value
The add method returns false if you attempt to add an element with a duplicate value
A set may contain elements that return duplicate values from a call to the equals method
An exception is thrown if you attempt to add an element with a duplicate value
The add method returns false if you attempt to add an element with a duplicate value
public class Y
{public void foo()
{
try {
b();
}
finally {
ba();
}
catch (MyException e) {}
}
public void b() throws X {
throw new X();
}public void ba() throws RuntimeException {
throw new RuntimeException();
}
}
Nothing is wrong with the code
Finally block should come after the catch block
An empty catch block is not allowed
None of the above
{public void foo()
{
try {
b();
}
finally {
ba();
}
catch (MyException e) {}
}
public void b() throws X {
throw new X();
}public void ba() throws RuntimeException {
throw new RuntimeException();
}
}
Nothing is wrong with the code
Finally block should come after the catch block
An empty catch block is not allowed
None of the above
Yes
No
No
Question16 What
will be the output of this program?public class Test
{
public static void main (String args[])
{String a, b, c, d;
a = ''Hello1234'';
b = ''Hello'' + String.valueOf(1234);
c = ''Hello'' + ''1234'';
d = new String (new char[]{'H', 'e', 'l', 'l', 'o', '1', '2', '3', '4'});
System.out.print (a == b);
System.out.print ('' '');
System.out.print (a.equals(b));
System.out.print ('' '');
System.out.print (a == c);
System.out.print ('' '');
System.out.print (a.equals(c));
System.out.print ('' '');
System.out.print (a == d);
System.out.print ('' '');
System.out.print (a.equals(d));
System.out.print ('' '');
}
}
true truetruetrue false true
false true truetrue false false
false true truetrue false true
false false true true false true
public static void main (String args[])
{String a, b, c, d;
a = ''Hello1234'';
b = ''Hello'' + String.valueOf(1234);
c = ''Hello'' + ''1234'';
d = new String (new char[]{'H', 'e', 'l', 'l', 'o', '1', '2', '3', '4'});
System.out.print (a == b);
System.out.print ('' '');
System.out.print (a.equals(b));
System.out.print ('' '');
System.out.print (a == c);
System.out.print ('' '');
System.out.print (a.equals(c));
System.out.print ('' '');
System.out.print (a == d);
System.out.print ('' '');
System.out.print (a.equals(d));
System.out.print ('' '');
}
}
true truetruetrue false true
false true truetrue false false
false true truetrue false true
false false true true false true
Question
18 Choose
the correct declarations for the main() method which will allow the
class to be run as a standalone program.
public void
main(String str[])
static public void main(String str[])
public static int main(String str[])
public static void main(String str[])
static public void main(String str[])
public static int main(String str[])
public static void main(String str[])
Question
19 For a
class defined inside a method, what rule governs access to the
variables of the enclosing method?
The class can
only access transient variables
The class can only access static variables
The class can only access final variables
The class can access any variable
The class can only access static variables
The class can only access final variables
The class can access any variable
Question
20 A
method can be defined as native to:
Overcome the
limitation of the private scope of a method
Get to access hardware that Java does not know about
Write optimized code for performance in a language such as C/C++
Define a new data type such as an unsigned integer
Get to access hardware that Java does not know about
Write optimized code for performance in a language such as C/C++
Define a new data type such as an unsigned integer
-2
2.0
-3
-3.0
2.0
-3
-3.0
Question
22 For the given variables, which of the following will compile
without an error?char c = 'c';
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