Java Interview Question and Answer SET 1
Core Java Placement Questions
1. What happens when the following program is
compiled and executed with the command - java test? Select the one correct
answer.
class test
{
public static void main (String args[])
{
If
(args.length > 0)
System.out.println(args.length);
}
}
(A) The program compiles and runs but does not print
anything.
(B) The program compiles and runs and prints 0
(C) The program
compiles and runs and prints 1
(D) The program compiles and runs and prints 2
2. What happens when the following program is
compiled and then the command "java
check it out" is executed. Select the one correct answer.
class check
{
public static void main(String
args[])
{
System.out.println(args[args.length-2]);
}
}
(A) The
program compiles but generates ArrayIndexOutOfBoundsException exception
(B) The
program prints java
(C) The program prints check
(D) The
program prints it
3. What all gets printed when the following gets
compiled and run. Select the two correct answers.
public class test {
public static void main(String args[]) {
String s1 = "abc";
String s2 = "abc";
if(s1 == s2)
System.out.println(1);
else
System.out.println(2);
if(s1.equals(s2))
System.out.println(3);
else
System.out.println(4);
}
}
(A) 1 2
(B) 1 3
(C) 1 4
(D) 2 4
4. What all gets printed when the following gets
compiled and run. Select the two correct answers.
public class test {
public
static void main(String args[]) {
String s1 = "abc";
String s2 = new String("abc");
if(s1 == s2)
System.out.println(1);
else
System.out.println(2);
if(s1.equals(s2))
System.out.println(3);
else
System.out.println(4);
}
}
(A) 1 3
(B) 1 4
(C) 2 3
(D) 2 4
5. What would be the results of compiling and
running the following class? Select the one correct answer.
class test
{
public static void main()
{
System.out.println("test");
}
}
(A) The program
compiles and runs but does not generate any output.
(B) The program
compiles and runs generating an output of "test"
(C) The program compiles but does not run.
(D) The program does
not compile as there is no main method defined
6. What are difference between break and continue?
Answers:
The break keyword halts the execution of the current loop
and forces control out of the loop.
The continue is similar to break, except that instead of halting
the execution of the loop, it starts the next iteration.
7. What is the difference between while statement
and a do statement?
Answers:
A while statement checks at the beginning of a loop to see
whether the next loop iteration should occur.
A do statement checks at the end of a loop to see whether
the next iteration of a loop should occur. The do statement will always execute
the body of a loop at least once.
8. How can class be imported to a program?
Answers:
To import a class, the import keyword should be used as
shown.;
import class name;
9. Constructors can be overloaded like regular
methods.
A) True
B) False
Answers: a.
10. You would use the ____ operator to create a
single instance of a named class.
a. New
b. dot
Answers: a.
11. A constructor is automatically called when an
object is instantiated.
a. true
b. false
Answers: a.
12. What are packages? What is use of packages?
Answers:
The package statement defines a name space in which classes
are stored. If you omit the package, the classes are put into the default
package.
Signature... package pkg;
Use: * It specifies to which package the classes defined in
a file belongs to. * Package is both naming and a visibility control mechanism.
13. User-defined package can also be imported just
like the standard packages.
True/False
Answers: True
14. All standard classes of Java are included within
a package called _____.
Answers: java.lang
15. All the classes in a package can be
simultaneously imported using ____.
Answers: *
16. What are different modifiers in java?
Answers: public, private, protected, default, static,
transient, volatile, final, abstract.
17. The Java language is:
a.
Interpreted at run time.
b.
Compiled to obtain executable
target files.
c.
Designed for recursive string
processing.
d.
Designed for matrix algorithm
processing.
18. In Java programs, the name of the class has to:
a.
Be the same as the name of the
file it is saved in.
b.
Be different from the name of
the file it is saved in.
c.
Be all capital letters.
d.
Be all small letters.
19. Encapsulation refers to the idea that:
a.
Instance variables can only be
accessed by means of methods.
b.
Methods can only be accessed by
means of instance variables.
c.
All other methods must be
defined within the main () method.
d.
Instance variables can only be
declared within methods.
20. In order to use objects of a given class the programmer needs to:
a.
Know what the methods do, but
not how they do it.
b.
Know all of the instance
variables of the class.
c.
Know how the method algorithms
were implemented.
d.
Know the types of all of the
instance variables of the class.
21. What is the return type of program’s main ( ) method?
22. What is the argument type of program’s main ( ) method?
23. What is the use of bin and lib in JDK?
24. What is the Extension of java byte codes?
A. .java
B. .class
C. .bc
D.
None of the Above
25. How many type of Primitive Data Types exist in Java?
5
7
8
10
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