Most 50 Java Interview Question & Answer

Which of the following is not a Java keyword?
a) static
b) Boolean
c) void
d) private
→ b) Boolean
Which company originally developed Java?
a) Sun Microsystems
b) Oracle
c) IBM
d) Microsoft
→ a) Sun Microsystems
Which method is the entry point of a Java program?
a) start()
b) run()
c) main()
d) init()
→ c) main()
What is the default value of an int variable in Java?
a) 0
b) null
c) undefined
d) 1
→ a) 0
Which of the following is used to compile Java code?
a) javac
b) java
c) javadoc
d) jar
→ a) javac

What is inheritance in Java?
a) Using functions
b) Creating new classes
c) Acquiring properties of one class by another
d) None
→ c) Acquiring properties of one class by another
Which keyword is used to inherit a class?
a) implement
b) extends
c) inherit
d) interface
→ b) extends
What is polymorphism?
a) Overloading
b) Overriding
c) Both a and b
d) None
→ c) Both a and b
Which of these is a superclass of all classes in Java?
a) Object
b) Class
c) Parent
d) Abstract
→ a) Object
What does encapsulation mean?
a) Binding data and code
b) Inheritance
c) Overloading
d) None
→ a) Binding data and code

Which data type is used to store a single character?
a) String
b) char
c) Character
d) int
→ b) char
What is the size of an int in Java?
a) 4 bytes
b) 2 bytes
c) 8 bytes
d) Depends on system
→ a) 4 bytes
Which operator is used for logical AND?
a) &
b) &&
c) |
d) ||
→ b) &&
Which type is not a primitive type?
a) int
b) float
c) boolean
d) String
→ d) String
What will be the result of 5/2 in Java?
a) 2.5
b) 2
c) 3
d) Error
→ b) 2

Which loop is guaranteed to execute at least once?
a) for
b) while
c) do-while
d) if
→ c) do-while
Which keyword is used to exit a loop?
a) exit
b) continue
c) return
d) break
→ d) break
What is used to skip current iteration in a loop?
a) break
b) return
c) continue
d) skip
→ c) continue
Which statement is used for decision-making?
a) for
b) if
c) do
d) loop
→ b) if
Which is the correct way to declare a switch statement?
a) switch(){}
b) switch case
c) switch(variable){}
d) if switch
→ c) switch(variable){ }

Which keyword is used to handle exceptions?
a) try
b) throw
c) catch
d) All of the above
→ d) All of the above
Which is a checked exception?
a) ArithmeticException
b) NullPointerException
c) IOException
d) ArrayIndexOutOfBoundsException
→ c) IOException
Which block is always executed?
a) catch
b) try
c) finally
d) throw
→ c) finally
How to throw an exception manually?
a) throws
b) throw
c) catch
d) try
→ b) throw
What does throws keyword indicate?
a) Code execution
b) Return type
c) Exception declaration
d) Loop
→ c) Exception declaration

Which keyword is used to create an object?
a) class
b) new
c) object
d) this
→ b) new
What is a constructor?
a) A variable
b) A method
c) A class
d) A block to initialize objects
→ d) A block to initialize objects
Which of these is not a valid constructor type?
a) Default
b) Static
c) Parameterized
d) Copy
→ b) Static
What is this keyword in Java?
a) Refers to parent object
b) Refers to current object
c) Refers to child class
d) Refers to static context
→ b) Refers to current object
Which block is used for final cleanup of object?
a) finalize()
b) cleanup()
c) destructor()
d) close()
→ a) finalize()

Which keyword is used to implement an interface?
a) inherit
b) extends
c) implements
d) override
→ c) implements
Can an interface contain constructor?
a) Yes
b) No
→ b) No
Can a class extend more than one class?
a) Yes
b) No
→ b) No
Can a class implement multiple interfaces?
a) Yes
b) No
→ a) Yes
Which is not a type of inheritance in Java?
a) Single
b) Hybrid
c) Multilevel
d) Multiple using class
→ b) Hybrid

Which is immutable in Java?
a) String
b) StringBuilder
c) Array
d) Collection
→ a) String
Which method is used to find string length?
a) size()
b) getLength()
c) length()
d) count()
→ c) length()
Which interface provides dynamic array in Java?
a) List
b) Array
c) Collection
d) Set
→ a) List
Which class implements List interface?
a) HashMap
b) ArrayList
c) HashSet
d) Hashtable
→ b) ArrayList
Which collection does not allow duplicates?
a) List
b) Set
c) ArrayList
d) Map
→ b) Set

Which method starts a thread execution?
a) run()
b) start()
c) execute()
d) init()
→ b) start()
Thread.sleep() pauses thread for:
a) seconds
b) milliseconds
c) microseconds
d) minutes
→ b) milliseconds
Which interface is used for threads?
a) Runnable
b) Threadable
c) Executable
d) Callable
→ a) Runnable
Which keyword is used for synchronization?
a) sync
b) synchronized
c) lock
d) mutex
→ b) synchronized
What is garbage collection in Java?
a) Memory allocation
b) Removing unused objects
c) Cleaning files
d) Managing exceptions
→ b) Removing unused objects

Java is a ______ language.
a) Platform dependent
b) Platform independent
c) Machine language
d) Scripting
→ b) Platform independent
Which memory is used by JVM to store objects?
a) Stack
b) Heap
c) Code
d) Class
→ b) Heap
Which keyword makes a variable constant?
a) constant
b) final
c) static
d) const
→ b) final
Which of these is not a Java feature?
a) Object-oriented
b) Architecture-neutral
c) Use of pointers
d) Robust
→ c) Use of pointers
Which package contains Scanner class?
a) java.util
b) java.io
c) java.lang
d) java.awt
→ a) java.util